Electrochemical display element and electrochemical display

ABSTRACT

An electrochemical display device and an electrochemical display apparatus, having preferable cycle properties and preferable display quality, and a method for producing the same. The electrochemical display device according to the present invention is characterized in that it has: a first transparent electrode; an electrolyte layer containing a coloring material which colors by a coloring means and electrochemical reduction or oxidation, accompanied by deposition or dissolution; a second electrode having the electrolyte layer disposed between the first transparent electrode and the second electrode; and a third electrode independent of the first transparent electrode and the second electrode.

TECHNICAL FIELD

The present invention relates to an electrochemical display device usinga principle such that the color of a material is changed utilizingelectrochemical oxidation or reduction.

BACKGROUND ART

In recent years, as the network widely spreads, documents, which haveconventionally been delivered in the form of prints, are being deliveredin the form of so-called electronic documents. Further, books, magazinesand the like are frequently provided through so-called electronicpublication.

The information has been read conventionally from a CRT or liquidcrystal display of a computer. However, it is pointed out that a lightemission type display causes severe fatigue for the reasons ofergonomics, making long-time reading difficult. In addition, there is adrawback in that information can be read only at the place in which acomputer is located.

Laptop computers widely spread currently, and some of them are used asportable display, but they cannot be used in reading for several hoursor longer because they are of a light emission type using a back lightand further consume the power soon. Recently, a reflection type liquidcrystal display is developed, and the use of this enables driving of acomputer with low power consumption; however, the liquid crystal hasonly a reflectance of plain display (white display) as low as 30%, andhence has markedly poor visibility, as compared to printed paper, and islikely to cause fatigue, thus also making long-time reading difficult.

For solving these problems, recently, so-called paper-like display orelectronic paper is being developed. They are colored mainly by makingcoloring particles to move between electrodes by an electrophoresismethod, or rotating particles having dichroism in an electric field.However, these methods have disadvantages in that spaces between theparticles absorb a light to lower the contrast, and the driving voltagerequired for obtaining a practical writing speed (1 second or faster) isas high as 100 V or more.

An electrochromic display apparatus (ECD), which achieves coloring basedon an electrochemical action, is preferable in contrast, as compared tothe above display using an electrophoresis method, and it has alreadybeen put into practical use in photochromic glass and clock display.However, the photochromic glass and clock display essentially have noneed of matrix driving, and hence cannot be applied to display use ofelectronic paper, and they generally have poor black quality and lowreflectance.

A display of electronic paper is always exposed to a light, such assunlight or room light, when being used. In the electrochromic displayapparatus practically used in photochromic glass and clock display, apredetermined organic material is used to form a black portion. However,an organic material generally has poor light resistance and hence posesa problem in that black color is faded and the black density is loweredafter being used for a long time. In addition, the display apparatus ofa matrix driving type described in Japanese Patent ApplicationPublication No. Hei 4-73764 is known, but the driving device merelyconstitutes a part of the liquid crystal display apparatus.

For solving the above technical problems, there have been proposed anelectrochemical display device and an electrochemical display apparatus,using metal ions as a material which changes in color by electrochemicaloxidation and reduction, and using a white colored polymer electrolytefor dissolving the metal ions, and being capable of matrix driving andimproving the contrast and the black density. However, the properties,especially cycle properties are unsatisfactory, and it is desired thatthe cycle properties are improved. In addition, there is a problem inthat appropriate control of the oxidation reduction reactions is notsatisfactorily achieved and the image remains upon display switching,that is, afterimage is caused, thus lowering the image quality.

In view of the above problems accompanying the prior art, the presentinvention has been made, and it is an object to provide anelectrochemical display device and an electrochemical display apparatus,having preferable cycle properties and preferable display quality, and amethod for producing the same.

DISCLOSURE OF THE INVENTION

The electrochemical display device according to the present inventionfor attaining the above object is characterized in that it has: a firsttransparent electrode; an electrolyte layer containing a coloringmaterial which colors by a coloring means and electrochemical reductionor oxidation, accompanied by deposition or dissolution; a secondelectrode having the electrolyte layer disposed between the firsttransparent electrode and the second electrode; and a third electrodeindependent of the first transparent electrode and the second electrode.

In the electrochemical display device according to the present inventionhaving the above configuration, by virtue of having the third electrodeindependent of the first transparent electrode and the second electrode,the reaction state during the deposition or dissolution of the coloringmaterial is precisely detected without being affected by the firsttransparent electrode and second electrode. Therefore, a point in timewhen the deposition or electrochemical reaction satisfactorily proceedsat the electrode is precisely detected, and driving is controlled basedon the result of detection, achieving precise control of the driving. Inaddition, the precise control of the driving prevents the reaction fromproceeding to an excess extent, so that the occurrence of a sidereaction due to the excess reaction is prevented.

In addition, the electrochemical display apparatus according to thepresent invention for attaining the above object includes a plurality ofelectrochemical display devices arranged in a plane form, wherein eachelectrochemical display device has: a first transparent electrode; anelectrolyte layer containing a coloring material which colors by acoloring means and electrochemical reduction or oxidation, accompaniedby deposition or dissolution; a second electrode having the electrolytelayer disposed between the first transparent electrode and the secondelectrode; and a third electrode independent of the first transparentelectrode and the second electrode.

In the electrochemical display apparatus according to the presentinvention having the above configuration, the electrochemical displaydevice constituting the electrochemical display apparatus has the thirdelectrode independent of the first transparent electrode and the secondelectrode, and hence the reaction state during the deposition ordissolution of the coloring material is precisely detected without beingaffected by the first transparent electrode and second electrode.Therefore, a point in time when the deposition or electrochemicalreaction satisfactorily proceeds at the electrode is precisely detected,and driving is controlled based on the result of detection, achievingprecise control of the driving. In addition, the precise control of thedriving prevents the reaction from proceeding to an excess extent, sothat the occurrence of a side reaction due to the excess reaction isprevented.

Further, the method for producing an electrochemical display deviceaccording to the present invention for attaining the above object has: astep for forming a first transparent electrode on a transparent support;a step for forming an electrolyte layer containing a coloring materialwhich colors by a coloring means and electrochemical reduction oroxidation, accompanied by deposition or dissolution; a step for forminga second electrode having the electrolyte layer disposed between thefirst transparent electrode and the second electrode; and a step forforming a third electrode independent of the first transparent electrodeand the second electrode.

In the above method for producing an electrochemical display deviceaccording to the present invention, the third electrode independent ofthe first transparent electrode and the second electrode is formed, andtherefore a device is produced in which the reaction state during thedeposition or dissolution of the coloring material is precisely detectedwithout being affected by the first transparent electrode and secondelectrode. Thus, there is produced an electrochemical display deviceadvantageous in that driving is precisely controlled to prevent theoccurrence of a side reaction due to the excess reaction.

Furthermore, the method for producing an electrochemical displayapparatus according to the present invention for attaining the aboveobject has: a step for forming a first transparent electrode on atransparent support; a step for forming an electrolyte layer containinga coloring material which colors by a coloring means and electrochemicalreduction or oxidation, accompanied by deposition or dissolution; a stepfor forming a second electrode having the electrolyte layer disposedbetween the first transparent electrode and the second electrode; and astep for forming a third electrode independent of the first transparentelectrode and the second electrode.

In the above method for producing an electrochemical display apparatusaccording to the present invention, the third electrode independent ofthe first transparent electrode and the second electrode is formed whenforming an electrochemical display device, and therefore a displayapparatus is produced in which the reaction state during the depositionor dissolution of the coloring material is precisely detected withoutbeing affected by the first transparent electrode and second electrode.Thus, there is produced an electrochemical display apparatusadvantageous in that driving is precisely controlled to prevent theoccurrence of a side reaction due to the excess reaction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing one example of the configuration ofan electrodeposition type display apparatus according to the presentinvention.

FIG. 2 is a cross-sectional view showing one example of theconfiguration of an electrodeposition type display apparatus accordingto the present invention.

FIG. 3 is a plan view showing one example of the configuration of anelectrodeposition type display apparatus according to the presentinvention.

FIG. 4 is a circuit diagram of an electrodeposition type displayapparatus according to the present invention.

FIG. 5 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 6 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 7 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 8 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 9 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 10 is an explanatory view illustrating the process for producing anelectrodeposition type display apparatus according to the presentinvention.

FIG. 11 is a cross-sectional view showing another example of theconfiguration of an electrodeposition type display apparatus accordingto the present invention.

FIG. 12 is a cross-sectional view showing another example of theconfiguration of an electrodeposition type display apparatus accordingto the present invention.

FIG. 13 is a perspective view showing one example of the configurationof an electrodeposition type display device in which the third electrodeis disposed on the side of the first transparent picture elementelectrode.

FIG. 14 is a plan view of the electrodeposition type display deviceshown in FIG. 13, as viewed from the top.

FIG. 15 is a perspective view showing one example of the configurationof an electrodeposition type display device in which the third electrodeis disposed on the side of the second electrode.

FIG. 16 is a plan view of the electrodeposition type display deviceshown in FIG. 15, as viewed from the top.

FIG. 17 is a perspective view showing an example of the configuration ofa conventional passive matrix-electrodeposition type display apparatus.

FIG. 18 is a plan view of the electrodeposition type display deviceshown in FIG. 17, as viewed from the top.

FIG. 19 is a plan view of the transparent picture element electrodesubstrate of the electrodeposition type display apparatus shown in FIG.17, as viewed from the counter electrode side.

FIG. 20 is an enlarged view of the essential portion indicated by anarrow B shown in FIG. 19.

FIG. 21 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a first embodiment, as viewed from the counter electrodeside.

FIG. 22 is an enlarged view of the essential portion indicated by anarrow C shown in FIG. 21.

FIG. 23 is an enlarged view of the essential portion indicated by anarrow D shown in FIG. 21.

FIG. 24 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a second embodiment, as viewed from the counter electrodeside.

FIG. 25 is an enlarged view of the essential portion indicated by anarrow E shown in FIG. 24.

FIG. 26 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a third embodiment, as viewed from the counter electrodeside.

FIG. 27 is an enlarged view of the essential portion indicated by anarrow F shown in FIG. 26.

FIG. 28 is an enlarged view of the essential portion indicated by anarrow G shown in FIG. 26.

FIG. 29 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a forth embodiment, as viewed from the counter electrodeside.

FIG. 30 is an enlarged view of the essential portion indicated by anarrow H shown in FIG. 29.

FIG. 31 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a fifth embodiment, as viewed from the counter electrodeside.

FIG. 32 is an enlarged view of the essential portion indicated by anarrow I shown in FIG. 31.

FIG. 33 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a sixth embodiment, as viewed from the counter electrodeside.

FIG. 34 is an enlarged view of the essential portion indicated by anarrow J shown in FIG. 33.

FIG. 35 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a seventh embodiment, as viewed from the counter electrodeside.

FIG. 36 is an enlarged view of the essential portion indicated by anarrow K shown in FIG. 35.

FIG. 37 is a plan view of the second electrode substrate of a passivematrix-electrodeposition type display apparatus in which the thirdelectrode is disposed on the side of the second electrode, as viewedfrom the counter electrode side.

FIG. 38 is an enlarged view of the essential portion indicated by anarrow L shown in FIG. 37.

FIG. 39 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a eighth embodiment, as viewed from the counter electrodeside.

FIG. 40 is an enlarged view of the essential portion indicated by anarrow M shown in FIG. 39.

FIG. 41 is an enlarged view of the essential portion indicated by anarrow N shown in FIG. 39.

FIG. 42 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a ninth embodiment, as viewed from the counter electrodeside.

FIG. 43 is an enlarged view of the essential portion indicated by anarrow O shown in FIG. 42.

FIG. 44 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a 10th embodiment, as viewed from the counter electrodeside.

FIG. 45 is an enlarged view of the essential portion indicated by anarrow P shown in FIG. 44.

FIG. 46 is an enlarged view of the essential portion indicated by anarrow Q shown in FIG. 44.

FIG. 47 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a 11th embodiment, as viewed from the counter electrodeside.

FIG. 48 is an enlarged view of the essential portion indicated by anarrow R shown in FIG. 47.

FIG. 49 is a plan view of the transparent picture element electrodesubstrate of a passive matrix-electrodeposition type display apparatusaccording to a 12th embodiment, as viewed from the counter electrodeside.

FIG. 50 is an enlarged view of the essential portion indicated by anarrow S shown in FIG. 49.

FIG. 51 is a cross-sectional view of a passive matrix-electrodepositiontype display apparatus according to a 13th embodiment.

FIG. 52 is a cross-sectional view of an active matrix type,electrodeposition type display apparatus in which the TFT for drivingand the third electrode are disposed on the side of the transparentpicture element electrode.

FIG. 53 is a plan view of the electrodeposition type display apparatusshown in FIG. 52, as viewed from the top.

FIG. 54 is a plan view of the transparent picture element electrode ofthe electrodeposition type display apparatus shown in FIG. 52, as viewedfrom the counter electrode side.

FIG. 55 is an enlarged view of the essential portion indicated by anarrow T shown in FIG. 54.

FIG. 56 is a plan view of the transparent picture element electrodesubstrate of an active matrix type electrodeposition type displayapparatus according to a 14th embodiment, as viewed from the counterelectrode side.

FIG. 57 is an enlarged view of the essential portion indicated by anarrow U shown in FIG. 56.

FIG. 58 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 15th embodiment, as viewed from the counterelectrode side.

FIG. 59 is an enlarged view of the essential portion indicated by anarrow V shown in FIG. 58.

FIG. 60 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 16th embodiment, as viewed from the counterelectrode side.

FIG. 61 is an enlarged view of the essential portion indicated by anarrow W shown in FIG. 60.

FIG. 62 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 17th embodiment, as viewed from the counterelectrode side.

FIG. 63 is an enlarged view of the essential portion indicated by anarrow X shown in FIG. 62.

FIG. 64 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 18th embodiment, as viewed from the counterelectrode side.

FIG. 65 is an enlarged view of the essential portion indicated by anarrow Y shown in FIG. 64.

FIG. 66 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 19th embodiment, as viewed from the counterelectrode side.

FIG. 67 is an enlarged view of the essential portion indicated by anarrow Z shown in FIG. 66.

FIG. 68 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 20th embodiment, as viewed from the counterelectrode side.

FIG. 69 is an enlarged view of the essential portion indicated by anarrow AA shown in FIG. 68.

FIG. 70 is a cross-sectional view of an active matrix type,electrodeposition type display apparatus in which the TFT for driving isdisposed on the side of the transparent picture element electrode andthe third electrode is disposed on the side of the counter electrode.

FIG. 71 is a plan view of the electrodeposition type display apparatusshown in FIG. 70, as viewed from the top.

FIG. 72 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a21st embodiment, as viewed from the counter electrode side.

FIG. 73 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a22nd embodiment, as viewed from the counter electrode side.

FIG. 74 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a23rd embodiment, as viewed from the counter electrode side.

FIG. 75 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a24th embodiment, as viewed from the counter electrode side.

FIG. 76 is an enlarged view of the essential portion indicated by anarrow AB shown in FIG. 75.

FIG. 77 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a25th embodiment, as viewed from the counter electrode side.

FIG. 78 is an enlarged view of the essential portion indicated by anarrow AC shown in FIG. 77.

FIG. 79 is a cross-sectional view of an active matrix type,electrodeposition type display apparatus according to a 26th embodiment.

FIG. 80 is a plan view of the second electrode substrate of an activematrix type, electrodeposition type display apparatus according to a27th embodiment, as viewed from the counter electrode side.

FIG. 81 is-a cross-sectional view of an active matrix type,electrodeposition type display apparatus in which the TFT for driving isdisposed on the side of the second electrode and the third electrode isdisposed on the side of the transparent picture element electrode.

FIG. 82 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 28th embodiment, as viewed from the counterelectrode side.

FIG. 83 is an enlarged view of the essential portion indicated by anarrow AD shown in FIG. 82.

FIG. 84 is an enlarged view of the essential portion indicated by anarrow AE shown in FIG. 83.

FIG. 85 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 29th embodiment, as viewed from the counterelectrode side.

FIG. 86 is an enlarged view of the essential portion indicated by anarrow AF shown in FIG. 85.

FIG. 87 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 30th embodiment, as viewed from the counterelectrode side.

FIG. 88 is an enlarged view of the essential portion indicated by anarrow AG shown in FIG. 87.

FIG. 89 is an enlarged view of the essential portion indicated by anarrow AH shown in FIG. 87.

FIG. 90 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 31st embodiment, as viewed from the counterelectrode side.

FIG. 91 is an enlarged view of the essential portion indicated by anarrow AI shown in FIG. 90.

FIG. 92 is a plan view of the transparent picture element electrodesubstrate of an active matrix type, electrodeposition type displayapparatus according to a 32nd embodiment, as viewed from the counterelectrode side.

FIG. 93 is an enlarged view of the essential portion indicated by anarrow AJ shown in FIG. 92.

FIG. 94 is a perspective view showing an electrode line structure havingno insulating layer.

FIG. 95 is a perspective view showing an electrode line structure havingan insulating layer perpendicular to the electrode line.

FIG. 96 is a perspective view showing an electrode line structure havingan insulating layer patterned to expose only the picture element portionand third electrode portion.

FIG. 97 is a plan view of the display electrode of the passivematrix-electrodeposition type display apparatus in Example 1, as viewedfrom the counter electrode side.

FIG. 98 is an enlarged view of the essential portion indicated by anarrow AK shown in FIG. 97.

FIG. 99 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 1.

FIG. 100 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 1.

FIG. 101 is a plan view of the display electrode of the active matrixtype, electrodeposition type display apparatus in Example 2, as viewedfrom the counter electrode side.

FIG. 102 is an enlarged view of the essential portion indicated by anarrow AL shown in FIG. 101.

FIG. 103 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 2.

FIG. 104 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 2.

FIG. 105 is a plan view of the counter electrode of the passivematrix-electrodeposition type display apparatus in Example 3, as viewedfrom the display electrode side.

FIG. 106 is an enlarged view of the essential portion indicated by anarrow AM shown in FIG. 105.

FIG. 107 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 3.

FIG. 108 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 3.

FIG. 109 is a characteristic diagram showing the results of the cyclicvoltammogram measurement with respect to the electrodeposition typedisplay apparatus in Example 4.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in detail withreference to the drawings. The present invention is not limited to thefollowing descriptions, and can be modified or changed as long as theeffect aimed at by the present invention is not deviated.

The electrochemical display device according to the present invention ischaracterized in that it has a first transparent electrode, anelectrolyte layer containing a coloring material which colors by acoloring means and electrochemical reduction or oxidation, accompaniedby deposition or dissolution, a second electrode having the electrolytelayer disposed between the first transparent electrode and the secondelectrode, and a third electrode independent of the first transparentelectrode and the second electrode. The electrochemical displayapparatus according to the present invention is characterized in that itincludes a plurality of the electrochemical display devices having theabove configuration and being arranged in a plane form.

FIG. 1 is a perspective view showing an essential portion of anelectrodeposition type display apparatus 1 which is an electrochemicaldisplay apparatus constituted by applying the present invention. FIG. 2is a cross-sectional view of FIG. 1, taken along the line A-A′, and FIG.3 is a plan view. As shown in FIGS. 1 to 3, the electrodeposition typedisplay apparatus 1 is characterized in that it includes a plurality ofelectrodeposition type display devices arranged in a plane form, each ofwhich has a transparent picture element electrode 3 which is a firsttransparent electrode controlled by a TFT (thin film transistor) 4serving as a driving device, an electrolyte layer 5 containing metalions and a coloring agent, a common electrode 6 as a second electrode,which is opposite to the first transparent electrode and common to thepicture elements, and a third electrode 8 on the same plane as that ofthe transparent picture element electrode 3.

In the electrodeposition type display apparatus 1, one transparentpicture element electrode 3 and one TFT 4 are combined to constitute onepicture element, and the picture elements are arranged in a matrix formon the transparent support 2.

As the transparent support 2, a transparent glass substrate, such as aquartz glass plate or a white glass plate, can be used, but it is notlimited to these, and examples include esters, such as polyethylenenaphthalate and polyethylene terephthalate; polyamide; polycarbonate;cellulose esters, such as cellulose acetate; fluorine polymers, such aspolyvinylidene fluoride andpolytetrafluoroethylene-cohexafluoropropylene; polyethers, such aspolyoxymethylene; polyacetal; polystyrene; polyolefins, such aspolyethylene, polypropylene, and methylpentene polymer; and polyimide,such as polyimide-amide and polyetherimide. When a synthetic resin isused as the support, either a rigid substrate unlikely to be bent or aflexible structure in a film form can be made.

The transparent picture element electrode 3 is comprised of atransparent conductive film formed in a substantially rectangular orsquare pattern, and, as shown in FIGS. 1 to 3, the picture elements areseparated from one another, and, in part of them, the TFT 4 is disposedper picture element. In the transparent picture element electrode 3, itis preferred to use a so-called ITO film included mainly of In₂O₃, SnO₂,or a mixture thereof or a thin film coated with SnO₂ or In₂O₃.Alternatively, one obtained by doping the ITO film or SnO₂- orIn₂O₃-coated film with Sn or Sb may be used, or MgO, ZnO or the like canbe used.

The TFT 4 formed in each picture element is selected by not shown wiringand controls the corresponding transparent picture element electrode 3.The TFT 4 is extremely effective in prevention of the occurrence ofcross talk between the picture elements. The TFT 4 may be formed, forexample, so as to occupy a corner of the transparent picture elementelectrode 3, but a structure may be employed in which the transparentpicture element electrode 3 is stacked on the TFT 4. In FIGS. 1 to 3,the TFT 4 is formed so as to occupy a corner of the transparent pictureelement electrode 3, but the TFT 4 may be formed so as to occupy acorner of the second electrode as described below. In this case, astructure may be employed in which the second electrode is stacked onthe TFT 4, and, when the TFT 4 is disposed at a corner of the secondelectrode, this structure is general.

To the TFT 4, specifically, are connected a gate line and a data line,and to each gate line is connected a gate electrode of each TFT 4, andone end of source/drain of each TFT 4 is connected to the data line, andanother end of source/drain is electrically connected to the transparentpicture element electrode 3. When the TFT 4 is provided at the secondelectrode, another end of source/drain is electrically connected to thesecond electrode. A driving device other than the TFT 4, such as adriving driver IC, may be comprised of other materials which can beformed on a transparent substrate as a matrix driving circuit used inflat display.

The electrolyte layer 5 containing metal ions can be constituted by anelectrolytic solution or a polymer electrolyte. As the electrolyticsolution, one containing a metal salt or a quaternary alkylammonium saltin a solvent can be used. As the solvent for the electrolytic solution,water, ethyl alcohol, isopropyl alcohol, propylene carbonate, dimethylcarbonate, ethylene carbonate, γ-butyrolactone, acetonitrile, sulfolane,dimethoxyethane, dimethylformamide, dimethyl sulfoxide, or a mixturethereof can be used.

As a matrix polymer used in the polymer electrolyte, preferred is apolymer material having a repeating unit of alkylene oxide,alkylenimine, or alkylene sulfide in a main skeleton unit or a sidechain unit, or both of them; a copolymer containing a plurality of thesedifferent units; or a polymethyl methacrylate derivative; polyvinylidenefluoride; polyvinylidene chloride; polyacrylonitrile; a polycarbonatederivative; or a mixture thereof. When the electrolyte layer iscomprised of a polymer electrolyte, the electrolyte layer comprised of apolymer electrolyte may be either of a single layer or a laminatestructure obtained by stacking a plurality of polymer electrolytelayers.

The above-mentioned matrix polymer can be used in the form of polymerswollen with water or an organic solvent. Especially when a highresponse speed or the like is required, the addition of the plasticizerfacilitates movement of the ions contained, and therefore it ispreferred that water or an organic solvent is added to the matrixpolymer.

When hydrophilicity is required according to the properties of thematrix polymer and the desired electrochemical reaction, it is preferredthat water, ethyl alcohol, isopropyl alcohol, or a mixture thereof isadded, and, when hydrophobicity is required, it is preferred thatpropylene carbonate, dimethyl carbonate, ethylene carbonate,γ-butyrolactone, acetonitrile, sulfolane, dimethoxyethane, ethylalcohol, isopropyl alcohol, dimethylformamide, dimethyl sulfoxide,dimethylacetamide, n-methylpyrrolidone, or a mixture thereof is added.

In the electrodeposition type display apparatus 1 according to thepresent invention, the electrolyte layer 5 contains metal ions as acoloring material which colors by electrochemical reduction oroxidation, accompanied by deposition or dissolution. The electrochemicaldeposition or dissolution reaction of the metal ions causes coloring ordecoloring to achieve display. In other words, a main principle is suchthat so-called plating and a dissolution reaction are advancedreversibly. With respect to the metal ions capable of coloring ordecoloring by electrochemical deposition or dissolution, there is noparticular limitation, and examples include ions of bismuth, copper,silver, sodium, lithium, iron, chromium, nickel, or cadmium and ionscomprised of a combination thereof. Of these, especially preferred metalions are bismuth and silver. The reason for this resides in that bismuthor silver can facilitate the reversible reaction, and exhibits highdegree of color change in the deposition.

When a salt containing an ion species different from the metal ionspecies to be deposited or dissolved is added as a supportingelectrolyte salt to the electrolyte layer 5, the electrochemicaldeposition or dissolution reaction can be carried out more effectivelyand stably. Examples of supporting electrolytes include lithium salts,such as LiCl, LiBr, LiI, LiBF₄, LiClO₄, LiPF₆, and LiCF₃SO₃; potassiumsalts, such as KCl, KI, and KBr; sodium salts, such as NaCl, NaI, andNaBr; and quaternary tetraalkylammonium salts, such astetraethylammonium borofluoride, tetraethylammonium perchlorate,tetrabutylammonium borofluoride, tetrabutylammonium perchlorate, andtetrabutylammonium halides. There may be a variation in the length ofalkyl chains in the above quaternary ammonium salts.

As a coloring means for improving the contrast, the electrolyte layer 5contains a coloring agent, such as an inorganic pigment or an organicpigment. When the color of the metal ions is black as mentioned above, awhite material having high opacifying properties is introduced as abackground color. As this material, for example, white particles forcoloring are used, and, as the white particles for coloring, titaniumdioxide, calcium carbonate, silica, magnesium oxide, or aluminum oxidecan be used. Alternatively, a dye for coloring can be used.

When inorganic particles are used as a coloring agent, the amount of thecoloring agent added is preferably 1 to 20 wt %, more preferably 1 to 10wt %, further preferably 5 to 10 wt %. In this case, when the amount ofthe coloring agent added is too small, desired coloring cannot beobtained, and, conversely, when the amount of the coloring agent addedis too large, the ion content is lowered and further the conductivity ofthe electrolyte is lowered. Accordingly, by using the coloring agent inthe above amount, preferable coloring conditions can be realized withoutcausing the above problems.

When inorganic particles as a coloring agent are mixed into theelectrolyte layer 5 comprised of a polymer electrolyte layer, thethickness of the electrolyte layer is preferably 20 to 200 μm, morepreferably 50 to 150 μm, further preferably 70 to 150 μm. When theelectrolyte layer has a smaller thickness, the resistance between theelectrodes is lowered, leading to advantages in that the time requiredfor coloring or decoloring becomes shorter and the power consumption isreduced. However, when the thickness of the electrolyte layer is 20 μmor less, the mechanical strength is disadvantageously lowered to cause apinhole or crack. Further, when the thickness of the electrolyte layeris too small, the content of the white particles is lowered, so that thewhiteness (optical density) is not satisfactory.

On the other hand, when a dye is used as the coloring means, the amountof the dye added may be as small as about 10 wt %. The reason for thisresides in that the coloring efficiency of the dye is considerably high,as compared to that of inorganic particles. Therefore, a dye which iselectrochemically stable can exhibit a satisfactory contrast even in asmall amount. Generally, as the dye, it is preferred to use anoil-soluble dye.

When the electrolyte layer 5 is comprised of a polymer electrolyte, theelectrolyte layer 5 comprised of a polymer electrolyte may have alaminate structure obtained by stacking a plurality of polymerelectrolyte layers, and, in this case, by providing the coloring meansonly in part of the layers, the above-mentioned effect can be obtained.

For reversibly and efficiently advancing the electrochemical reactions,especially deposition and dissolution of a metal, it is preferred thatat least one additive selected from a growth inhibitor, a stressrelaxing agent, a brightener, a complexing agent, and a reducing agentis added to the electrolyte layer 5. As the additive, an organiccompound having a group having an oxygen atom or a sulfur atom ispreferred, and, for example, at least one member selected from the groupcomprised of thiourea, 1-allyl-2-thiourea, mercaptobenzimidazole,coumarin, phthalic acid, succinic acid, salicylic acid, glycolic acid,dimethylamineborane (DMAB), trimethylamineborane (TMAB), tartaric acid,oxalic acid, and D-glucono-1,5-lactone can be added. Particularly, inthe present invention, when adding mercaptobenzimidazole according to amercaptoalkylimidazole represented by the chemical formula 1 below, notonly be the reversibility improved, but also preferable effects can beadvantageously obtained in long-term storage properties andhigh-temperature storage properties.Chemical Formula 1

where each of R1, R2, and R3 is a hydrogen atom or alkyl substituentrepresented by C_(n)H₂₊₁ (wherein n is an integer of 0 or more).

In the electrodeposition type display apparatus of a system having theabove configuration, a side reaction other than the predeterminedreactions may be caused during the electrochemical reactions. Forexample, when the electrolyte layer 5 contains a salt containing ahalide, the halide in the form of ions is oxidized depending on thepotential according to the reaction represented by the chemical formula2 below, thus causing coloring other than the desired coloring.I₂+2e−

2I−(0.536V)   Chemical formula 2Br₂+2e−

2Br−(1.065V)Cl₂+2e−

2Cl−(1.360V)(The values indicate standard electrode potentials in an aqueoussolution.)

Therefore, for preventing the occurrence of unnecessary coloring, it isrequired to suppress the above side reaction and reduce the halideoxidized. In this case, as a reducing agent, a general reducing agentcan be used and added as an additive to the electrolyte layer 5. As thereducing agent, for example, an ascorbic acid compound, atrialkylalcoholamine having a general formula represented by thechemical formula 3 below, or the like is preferred.Chemical Formula 3

Particularly, in the present invention, when triethanolamine representedby the chemical formula 4 below which is a trialkylalcoholamine speciesis added to the electrolyte layer 5, preferable effects can beadvantageously obtained in long-term storage properties andhigh-temperature storage properties.

When a reduction reaction is caused due to a side reaction other thanthe predetermined reaction, an oxidizing agent is added. Therefore, itis preferred that the electrolyte layer contains a reducing agent or anoxidizing agent for suppressing a side reaction which is possibly causedin any of the first transparent electrode and the second electrodemainly due to an anion species during the deposition of the coloringmaterial.Chemical Formula 4

As the second electrode disposed opposite to the first transparentelectrode, a common electrode 6 is formed. The common electrode 6 may becomprised of any metal which is electrochemically stable, but preferredare platinum, chromium, aluminum, cobalt, palladium, bismuth, andsilver, and it can be prepared by forming a film comprised of a goodconductor, such as a metallic thin film, on the support 7. Further, whenit is possible to preliminarily or successively, satisfactorily make upfor the metal used in the main reaction, carbon can be used in thecommon electrode. The use of carbon can lower the cost for theelectrode. As an example of a method for carrying carbon on theelectrode, there can be mentioned a method in which an ink is formedfrom carbon using a resin and printed on the surface of the substrate.

In the system in which bismuth or silver is deposited or dissolved, whenthe same metal species as that to be deposited or dissolved is used asthe second electrode, electrochemically stable electrode reactions canbe realized.

The support 7 is not necessarily transparent, and a substrate or a film,which can surely support the common electrode 6 and the electrolytelayer 5, can be used. For example, a quartz glass plate, a white glassplate, a ceramic substrate, a paper substrate, a wooden substrate, orthe like can be used, but the support is not limited to these, and, as asynthetic resin substrate, ester, such as polyethylene naphthalate orpolyethylene terephthalate; polyamide; polycarbonate; cellulose ester,such as cellulose acetate;

a fluorine polymer, such as polyvinylidene fluoride orpolytetrafluotoethylene-cohexafluoropropylene; polyether, such aspolyoxymethylene; polyacetal; polystyrene; polyolefin, such aspolyethylene, polypropylene, or methylpentene polymer; or polyimide,such as polyimide-amide or polyetherimide can be used.

When the above synthetic resin is used as the support 7, either a rigidsubstrate unlikely to be bent or a flexible structure in a film form canbe made. When the second electrode is integrally constituted as thecommon electrode and has satisfactory rigidity, there is no need to formthe support 7.

For disposing the first transparent electrode opposite to the secondelectrode as shown in FIGS. 1 to 3, sealing resin portions 9 for holdingboth the supports 2, 7 are formed on the periphery. The sealing resinportions 9 surely hold the both supports 2, 7, and the transparentpicture element electrodes 3, TFTs 4, electrolyte layer 5, and commonelectrode 6 disposed between the supports.

The third electrode 8 is formed as a member which is independent of andelectrically insulated from the transparent picture element electrode 3and the common electrode 6. The third electrode 8, which is formed as amember independent of and electrically insulated from the transparentpicture element electrode 3 and the common electrode 6, can preciselydetect the state of the reaction which proceeds during the deposition ordissolution of the coloring material without being affected by thetransparent picture element electrode 3 and common electrode 6.

As a material for the third electrode 8, a stable metal material whichis not involved in the reaction at all and is not dissolved in thereaction medium is selected and, for example, the same material as thatfor the common electrode 6, such as platinum, chromium, aluminum,cobalt, palladium, or silver, can be selected.

FIG. 4 is a circuit diagram of the electrodeposition type displayapparatus 1. Picture elements comprised of the TFT 4 and the transparentpicture element electrode 3 are arranged in a matrix form, and a commonelectrode is on the counter electrode side of a capacitor. Data linedriving circuits 12, 12 a and gate line driving circuit 13 for selectingthe individual picture elements are provided, and predetermined dataline 15 and gate line 14 are individually selected by a signal from asignal control portion 11. The third electrode 8 is connected from thesignal control portion 11, and the potential of the picture elementportion can be monitored by a signal from the third electrode 8, so thatthe state of the reaction which proceeds during the deposition ordissolution of the metal can be precisely detected without beingaffected by the transparent picture element electrode 3 and commonelectrode 6.

In the electrodeposition type display apparatus 1 according to thepresent invention having the above-described configuration, matrixdriving using the TFT 4 is possible. In addition, by utilizing the metalions and coloring agent contained in the electrolyte layer 5, there canbe realized an electrodeposition type display apparatus which isadvantageous not only in that it enables display with preferablecontrast and high black density, but also in that it exhibits preferabledisplay quality and preferable visibility.

Further, in the electrodeposition type display apparatus according tothe present invention having the above configuration, electricity isconducted between the transparent picture element electrode 3 as thefirst transparent electrode and the second electrode 6 to allow ions inthe electrolyte layer disposed between the transparent picture elementelectrode 3 and the second electrode 6 to move, so that anelectrochemical reaction proceeds to cause deposition or dissolution ofthe metal, thus changing a color and coloring. The electrolyte layer 5contains a coloring agent as the coloring means, and hence can improvethe contrast when the coloring material changes in color.

In an electrodeposition type display apparatus having a structureincluding only the first transparent electrode and the second electrodeand having no third electrode, for example, when being controlled by avoltage waveform, not only the potential of the first transparentelectrode but also the potential of the second electrode vary due to theelectrochemical reaction, so that the potential difference between thetwo electrodes is controlled by an external voltage waveform in a statesuch that both the potentials are varying. When such controlling isconducted, the inherent potential of the first transparent electrodecannot be known, making desired controlling difficult. This means thatthe coloring material cannot be controlled to be in a desired dissolvedor deposited state. Therefore, in systems other than the system in whichthere is almost no variation in the potential of the second electrode,control of the potential difference between the two electrodes by anexternal voltage waveform is poor in reliability.

By contrast, in the electrodeposition type display apparatus 1, whendisplay is achieved by conducting electricity between the transparentpicture element electrode 3 as the first transparent electrode and thecommon electrode 6 to change a color, the third electrode 8 as areference electrode, which is insulated from and independent of thetransparent picture element electrode 3 and the common electrode 6, isnot directly involved in the electrochemical reaction.

Thus, the state of the reaction which proceeds during the deposition ordissolution of the coloring material can be precisely detected withoutbeing affected by the transparent picture element electrode 3 and commonelectrode 6. In other words, using as a reference the potential of thethird electrode 8 which does not vary, the reaction state during thedeposition or dissolution of the coloring material can be detected orswept as a potential, thus making it possible to precisely detect apoint in time when deposition or electrochemical reaction satisfactorilyproceeds at the electrode. Then, based on the result of detection,driving, i.e., conduction between the transparent picture elementelectrode 3 and the second electrode 6 is controlled, enabling controlof the electrochemical reaction with high reliability.

This means that the coloring material can be controlled to be in adesired dissolved or deposited state, so that control of coloring ordecoloring of the coloring material, namely, control of display can beappropriately conducted, thus enabling control of display with highreliability.

Accordingly, the occurrence of a phenomenon in which the color remainsupon decoloring, i.e., so-called afterimage can be prevented, thusmaking it possible to constitute an electrodeposition type displayapparatus having preferable visibility. Therefore, in theelectrodeposition type display apparatus 1, an electrodeposition typedisplay apparatus having preferable display quality is realized.

When appropriate control of driving is not made in the electrodepositiontype display apparatus, the reaction proceeds to an excess extent tocause a side reaction, leading to deterioration of the cycle properties.

However, in the electrodeposition type display apparatus 1, as mentionedabove, the third electrode 8 is formed as a member which is independentof and electrically insulated from the transparent picture elementelectrode 3 and the common electrode 6, making it possible to preciselydetect a point in time when deposition or electrochemical reactionsatisfactorily proceeds at the electrode. Then, based on the result ofdetection, driving, i.e., conduction between the transparent pictureelement electrode 3 and the second electrode 6 is controlled to preventthe reaction from further proceeding. That is, this control can preventa side reaction due to the excess deposition or dissolution reaction ofthe coloring material, so that deterioration of the cycle properties dueto a side reaction other than the predetermined reactions can beprevented, thus remarkably improving the cycle properties. Therefore, inthe electrodeposition type display apparatus 1, the use of the thirdelectrode 8 has realized an electrodeposition type display apparatushaving preferable cycle properties.

Next, a method for producing the above-described electrodeposition typedisplay apparatus 1 is described. In the production of theelectrodeposition type display apparatus 1, first, as shown in FIG. 5,on a transparent support 2 comprised of a glass substrate or the like,transparent picture element electrodes 3 comprised of an ITO film andTFTs 4 are formed. The ITO film can be formed by a conventionally knownmethod, such as vapor deposition or sputtering, and the TFT 4 can beformed using a known technique for fabrication of semiconductor. In thiscase, prior to formation of the transparent picture element electrodes3, the transparent support 2 may be subjected to treatment for improvingthe adhesion. The transparent picture element electrode 3 and the TFT 4are formed per picture element, and the picture elements are arranged ina matrix form on the transparent support 2. Between the picture elementsare formed third electrodes 8 comprised of silver by a conventionallyknown method, such as vapor deposition, sputtering, or plating. In thesubsequent step, lead portions (not shown) which can be connected todriving circuits are formed. In the case of a passive matrix structure,a desired thin film is formed on the entire surface, and then patternedby a known resist technique to form a desired stripe form.

Then, an electrolyte layer 5 is formed on the transparent support 2.When, for example, a polymer electrolyte layer is formed as theelectrolyte layer 5, first, a synthetic resin as a matrix polymer forthe polymer solid electrolyte, a salt constituting the electrolyte andcontaining a metal species to be deposited or dissolved, and asupporting electrolyte salt are mixed together, and white particles as acoloring agent and a plasticizer are added thereto and dispersed.

Separately, as shown in FIG. 6, as a preliminary step for application ofthe polymer electrolyte material, the transparent support 2 is subjectedto UV ozone treatment for cleaning and surface modification.

Then, as shown in FIG. 7, the polymer electrolyte material is appliedonto the transparent support 2 after being subjected to UV ozonetreatment to form the electrolyte layer 5. As the salt constituting theelectrolyte and containing a metal species to be deposited or dissolved,for example, a silver salt or a bismuth salt can be used, and, as thesupporting electrolyte salt, a material, such as a lithium salt, apotassium salt, a sodium salt, or a tetraalkylammonium salt, can beused. As the coloring agent, for example, titanium oxide or aluminumoxide can be used.

Then, as shown in FIG. 8, on a support 7 comprised of, for example,polyethylene terephthalate, a common electrode 6 comprised of apalladium film having a desired thickness is formed. The commonelectrode 6 is formed by a conventionally known method, such as vapordeposition, sputtering, or plating, on the support 7 which has beensubjected to treatment for improving the adhesion.

Then, as shown in FIG. 9, the support 7 is stacked on the electrolytelayer 5 comprised of a polymer electrolyte so that the common electrode6 faces the electrolyte layer 5. Then, as shown in FIG. 10, sealingresin portions 9 are formed at the edges of the resultant laminate usinga general-purpose sealing agent to seal the display portion, thusproducing the electrodeposition type display apparatus 1.

Then, the matrix polymer in the polymer electrolyte having high fluiditymay be permitted to undergo a cross-linking reaction by a heating orultraviolet irradiation means to make gelation. In this case, across-linking agent or a photosensitizer can be used to efficientlypromote the gelation.

Alternatively, before forming the electrolyte layer 5 comprised of apolymer electrolyte, the transparent support 2 and the support 7 maybestacked in a state such that a desired gap between the electrodes isformed using a partition or the like to secure an injection inlet for apolymer electrolyte solution having fluidity. Then, as conducted in theprocess for liquid crystal, a polymer electrolyte solution havingfluidity is injected by an injection method utilizing capillaryphenomena, and then the injection inlet is sealed up, thus producing theelectrodeposition type display apparatus 1. By using the injectionmethod, an electrolytic solution containing no resin and a solutioncontaining a coloring agent are injected, thus constituting theelectrodeposition type display apparatus 1.

For keeping the gap between the transparent support 2 and the support 7stacked to face each other constant in the in-plane direction, aframe-form gap-forming member comprised of a resin, an inorganicmaterial or the like may be provided at the outer periphery portion ofthe transparent support 2 and the support 7, or fine spheres used in aliquid crystal device or the like can be dispersed in the polymerelectrolyte to form a desired gap. Alternatively, nonwoven fabric or aporous film containing a polymer electrolyte can be used as agap-forming member.

The active matrix type in which the third electrode 8 is disposed on thefirst transparent electrode side, i.e., transparent picture elementelectrode side is described above, but the present invention is notlimited to this type. The above-described electrochemical display deviceis roughly classified into an active matrix type and a passive matrixtype (simple matrix type). The active matrix type includes a type havingthe TFT incorporated to the side of the first transparent electrode as aworking electrode as mentioned above, and a type having the TFTincorporated to the side of the second electrode as a counter electrode.

In the active matrix type, considering the opening ratio of the displaypicture element, the latter type having the TFT incorporated to the sideof the second electrode is preferred since the TFT does not reduce theopening area. For further utilizing the effectiveness of the thirdelectrode as a reference electrode disposed on the side of the firsttransparent electrode, it is preferred that the third electrode is closeto the working electrode, and, in this case, the former type having theTFT incorporated to the side of the first transparent electrode ispreferred. Further, the structure for the third electrode includes astructure in which the third electrode is disposed on the side of thefirst transparent electrode and a structure in which the third electrodeis disposed on the side of the second electrode as a counter electrode.

FIG. 11 is a cross-sectional view showing one example of theconfiguration of an electrodeposition type display device of the lattertype having the TFT incorporated to the side of the second electrode asa counter electrode. The electrodeposition type display device isconfigured by having second electrodes 25, which are formed on a support27 and controlled by TFTs 26 serving as driving devices, an electrolytelayer 24, first transparent electrodes 22 opposite to the secondelectrodes 25, and third electrodes 23. The first transparent electrodes22 are formed in a stripe form on a transparent support 21, and thethird electrode 23 is disposed on the transparent support 21 per stripeof the first transparent electrode 22. The electrolyte layer 24 iscomprised of an electrolytic solution or a polymer electrolyte, whichcontain metal ions and a coloring agent, and the gap portion between thefirst transparent electrodes 22 and the second electrodes 25 is filledwith the electrolyte layer.

The third electrode can be formed by weaving a thin metal wire into amesh form, and a structure can be employed in which the thus formedthird electrode is sandwiched with nonwoven fabric and disposed betweenthe first transparent electrodes and the second electrodes so as toprevent the occurrence of short-circuiting between the third electrodeand the other electrodes.

FIG. 12 is a cross-sectional view showing one example of theconfiguration of the electrodeposition type display device shown in FIG.1 having a third electrode formed by weaving a thin metal wire into amesh form. The electrodeposition type display device is configured byhaving transparent picture element electrodes 3 as first transparentelectrodes controlled by TFTs 4 serving as driving devices, anelectrolyte layer 5, a common electrode 6 as a second electrode, whichis opposite to the first transparent electrodes and common to thepicture elements, and a third electrode 31. The third electrode 31 isformed by weaving a thin metal wire into a mesh form, and sandwichedwith nonwoven fabric 32 and then disposed between the transparentpicture element electrodes 3 and the common electrode 6 so as to preventthe occurrence of short-circuiting between the third electrode and theother electrodes. The electrolyte layer 5 is comprised of anelectrolytic solution or a polymer electrolyte, which contain metal ionsand a coloring agent, and the gap portion between the first transparentpicture element electrode 3 and the common electrode 6 is filled withthe electrolyte layer.

On the other hand, the passive matrix type includes a type having thethird electrode disposed on the side of the first transparent electrodeas a working electrode and a type having the third electrode disposed onthe side of the second electrode as a counter electrode.

FIG. 13 is a perspective view showing one example of the configurationof an electrodeposition type display device of the former type havingthe third electrode disposed on the side of the first transparentelectrode. The electrodeposition type display device is configured byhaving transparent picture element electrodes 42 formed in a stripe formon a transparent support 41, an electrolyte layer 46, second electrodes45, which are formed in a stripe form on a support 44 facing thetransparent picture element electrodes 42, and third electrodes 43. Asshown in FIG. 14, the transparent picture element electrodes 42 and thesecond electrodes 45 are arranged so that the individual stripestructures cross at a right angle, and the crossing portions of thestripe structures correspond to display active regions. The thirdelectrodes 43 are arranged in a stripe form in the same number as thatof the stripes of the transparent picture element electrodes 42 on thesame substrate on which the transparent picture element electrodes 42are formed in a stripe form, namely, on the transparent support 41 sothat the stripes of the third electrodes 43 are parallel to those of thetransparent picture element electrodes 42. The electrolyte layer 46 iscomprised of an electrolytic solution or a polymer electrolyte, whichcontain metal ions and a coloring agent, and the gap portion between thefirst transparent picture element electrodes 42 and the secondelectrodes 45 is filled with the electrolyte layer 46.

FIG. 15 is a perspective view showing one example of the configurationof an electrodeposition type display device of the latter type havingthe third electrode disposed on the side of the second electrode. Theelectrodeposition type display device is configured by havingtransparent picture element electrodes 42 formed in a stripe form on atransparent support 41, an electrolyte layer 46, second electrodes 45formed in a stripe form on a support 44, and third electrodes 43. Asshown in FIG. 16, the transparent picture element electrodes 42 and thesecond electrodes 45 are arranged so that the individual stripestructures cross at a right angle, and the crossing portions of thestripe structures correspond to display active regions. The thirdelectrodes 43 are arranged in a stripe form in the same number as thatof the stripes of the second electrodes 45 on the same substrate onwhich the second electrodes 45 are formed in a stripe form, namely, onthe support 44 so that the stripes of the third electrodes 43 areparallel to those of the second electrodes 45. The electrolyte layer 46is comprised of an electrolytic solution or a polymer electrolyte, whichcontain metal ions and a coloring agent, and the gap portion between thefirst transparent picture element electrodes 42 and the secondelectrodes 45 is filled with the electrolyte layer 46.

Hereinbelow, examples of arrangement of the third electrode in theelectrodeposition type display device according to the present inventionare shown as specific embodiments of the present invention.

First, examples of the configuration of a passivematrix-electrodeposition type display device in which the thirdelectrode is arranged on the side of the transparent picture elementelectrode are described. In the following first to seventh embodiments,the basic configuration of the electrodeposition type display device isthe configuration of a conventional standard passivematrix-electrodeposition type display device in which no third electrodeis provided, i.e., configuration shown in FIG. 17 and FIG. 18.Specifically, the device includes transparent picture element electrodes52 formed in a stripe form on a transparent support 51, an electrolytelayer 55, and second electrodes 54 which are formed in a stripe form ona support 53 facing the transparent picture element electrodes 52. Asshown in FIG. 19, both ends of the transparent picture elementelectrodes 52 are connected to transparent picture element electrodewithdrawal portions 56 and transparent picture element electrodewithdrawal portions 57. As shown in FIG. 20, on the transparent pictureelement electrodes 52, insulating layers 58 are formed so as to beperpendicular to the transparent picture element electrodes 52. FIG. 19is a plan view of the transparent support 51 as viewed from the counterelectrode side, and FIG. 20 is an enlarged view of the essential portionindicated by an arrow B shown in FIG. 19. Hereinbelow, an explanation ismade with reference to the plan view of the transparent support 51 onwhich the transparent picture element electrodes 52 are formed(hereinafter, frequently referred to as “transparent picture elementelectrode substrate”), as viewed from the counter electrode side, andthe enlarged view of the essential portion.

FIRST EMBODIMENT

The first embodiment is an example of the arrangement in which a thirdelectrode 59 in a line form is arranged on the transparent pictureelement electrode substrate so as to surround the whole of the effectivepicture elements on the side of the transparent picture elementelectrodes 52 as shown in FIG. 21. The third electrode 59 is connectedto third electrode withdrawal portions 60, 61, 62, 63. As shown in FIG.22, on the transparent picture element electrodes 52, insulating layers58 are formed so as to be perpendicular to the transparent pictureelement electrodes 52. At the portion on which the third electrode 59 isdisposed, as shown in FIG. 23, the third electrode 59 is formed on theinsulating layer 58. When the third electrode is arranged so as tosurround the whole of the effective picture elements as described above,the opening ratio can be increased, making it possible to constitute anelectrodeposition type display device having preferable light withdrawalefficiency.

SECOND EMBODIMENT

The second embodiment is an example of the arrangement in which top andbottom third electrodes 59 in a line form are arranged, on thetransparent picture element electrode substrate, in the directionparallel to the stripe structure of the transparent picture elementelectrodes 52 so that the whole of the effective picture elements aredisposed between the two third electrodes as shown in FIG. 24. The topand bottom third electrodes 59 are connected, respectively, to thirdelectrode withdrawal portions 60, 61 and third electrode withdrawalportions 62, 63. As shown in FIG. 25, on the transparent picture elementelectrodes 52, insulating layers 58 are formed so as to be perpendicularto the transparent picture element electrodes 52. When the top andbottom third electrodes are arranged so that the whole of the effectivepicture elements are disposed between the two third electrodes asdescribed above, the opening ratio can be increased, making it possibleto constitute an electrodeposition type display device having preferablelight withdrawal efficiency.

THIRD EMBODIMENT

The third embodiment is an example of the arrangement in which right andleft third electrodes 59 in a line form are arranged, on the transparentpicture element electrode substrate, in the direction perpendicular tothe stripe structure of the transparent picture element electrodes 52 sothat the whole of the effective picture elements are disposed betweenthe right and left third electrodes as shown in FIG. 26. The right andleft third electrodes 59 are connected, respectively, to third electrodewithdrawal portions 60, 63 and third electrode withdrawal portions 61,62. As shown in FIG. 27, on the transparent picture element electrodes52, insulating layers 58 are formed so as to be perpendicular to thetransparent picture element electrodes 52. At the portion on which thethird electrode 59 is disposed, as shown in FIG. 28, the third electrode59 is formed on the insulating layer 58. When the two third electrodesare arranged so that the whole of the effective picture elements aredisposed between the right and left third electrodes as described above,the opening ratio can be increased, making it possible to constitute anelectrodeposition type display device having preferable light withdrawalefficiency.

FORTH EMBODIMENT

The forth embodiment is an example of the arrangement in which thirdelectrodes 59 in a line form in the same number as that of the stripesof the transparent picture element electrodes 52 are formed, on thetransparent picture element electrode substrate, in the directionparallel to the stripe structure of the transparent picture elementelectrodes 52 between the stripes of the transparent picture elementelectrodes 52 as shown in FIG. 29. The third electrodes 59 areindividually connected to third electrode withdrawal portions 60 andthird electrode withdrawal portions 61. As shown in FIG. 30, on thetransparent picture element electrodes 52 and the third electrodes 59,insulating layers 58 are formed so as to be perpendicular to thetransparent picture element electrodes 52 and third electrodes 59.

FIFTH EMBODIMENT

The fifth embodiment is an example of the arrangement in which thirdelectrodes 59 in a line form are formed, on the transparent pictureelement electrode substrate, in the direction parallel to the stripestructure of the transparent picture element electrodes 52 at intervalsof the predetermined number of the stripes of the transparent pictureelement electrodes 52 as shown in FIG. 31. The third electrodes 59 areindividually connected to third electrode withdrawal portions 60 andthird electrode withdrawal portions 61. As shown in FIG. 32, on thetransparent picture element electrodes 52 and the third electrodes 59,insulating layers 58 are formed so as to be perpendicular to thetransparent picture element electrodes 52 and third electrodes 59.

SIXTH EMBODIMENT

The sixth embodiment is an example of the arrangement in which thirdelectrodes 59 in a line form are formed, on the transparent pictureelement electrode substrate, in the direction perpendicular to thestripe structure of the transparent picture element electrodes 52between the picture elements in the lengthwise direction as shown inFIG. 33. The third electrodes 59 are individually connected to thirdelectrode withdrawal portions 60 and third electrode withdrawal portions61. As shown in FIG. 34, the third electrodes 59 in the same number asthat of insulating layers 58 are formed on the insulating layers 58formed in the direction perpendicular to the stripe structure of thetransparent picture element electrodes 52.

SEVENTH EMBODIMENT

The seventh embodiment is an example of the arrangement in which thirdelectrodes 59 in a line form are formed, on the transparent pictureelement electrode substrate, in the direction perpendicular to thestripe structure of the transparent picture element electrodes 52between the picture elements in the lengthwise direction atpredetermined intervals as shown in FIG. 35. The third electrodes 59 areindividually connected to third electrode withdrawal portions 60 andthird electrode withdrawal portions 61. As shown in FIG. 36, the thirdelectrodes 59 are formed on insulating layers 58 formed in the directionperpendicular to the stripe structure of the transparent picture elementelectrodes 52 at intervals of the predetermined number of the insulatinglayers 58.

Next, examples of the configuration of a passivematrix-electrodeposition type display device in which the thirdelectrode is arranged on the side of the second electrode are described.In the following eighth to twelfth embodiments, the basic configurationof the electrodeposition type display device is the same as that in thefirst to seventh embodiments, i.e., configuration shown in FIG. 17 andFIG. 18. Specifically, the device includes transparent picture elementelectrodes 52 formed in a stripe form on a transparent support 51, anelectrolyte layer 55, and second electrodes 54 which are formed in astripe form on a support 53 facing the transparent picture elementelectrodes. As shown in FIG. 37, both ends of the second electrodes 54are connected to second electrode withdrawal portions 71, 72. As shownin FIG. 38, on the second electrodes 54, insulating layers 73 are formedso as to be perpendicular to the second electrodes 54. FIG. 37 is a planview of the support 53 as viewed from the counter electrode side, andFIG. 38 is an enlarged view of the essential portion indicated by anarrow L shown in FIG. 37. Hereinbelow, an explanation is made withreference to the plan view of the support 53 on which the secondelectrodes are formed (hereinafter, frequently referred to as “secondelectrode substrate”), as viewed from the counter electrode side, andthe enlarged view of the essential portion.

EIGHT EMBODIMENT

The eighth embodiment is an example of the arrangement in which a thirdelectrode 74 in a line form is arranged on the second electrodesubstrate so as to surround the whole of the effective picture elementson the side of the second electrodes 54 as shown in FIG. 39. The thirdelectrode 74 is connected to third electrode withdrawal portions 75, 76,77, 78. As shown in FIG. 40, on the second electrodes 54, insulatinglayers 73 are formed so as to be perpendicular to the second electrodes54. At the portion on which the third electrode 74 is disposed, as shownin FIG. 41, the third electrode 74 is formed on the insulating layer 73.

NINTH EMBODIMENT

The ninth embodiment is an example of the arrangement in which right andleft third electrodes 74 in a line form are formed, on the secondelectrode substrate, in the direction parallel to the stripe structureof the second electrodes 54 so that the whole of the effective pictureelements are disposed between the right and left third electrodes 74 asshown in FIG. 42. The right and left third electrodes 74 are connected,respectively, to third electrode withdrawal portions 75, 78 and thirdelectrode withdrawal portions 76, 77. As shown in FIG. 43, on the secondelectrodes 54, insulating layers 73 are formed so as to be perpendicularto the second electrodes 54.

10TH EMBODIMENT

The 10th embodiment is an example of the arrangement in which top andbottom third electrodes 74 in a line form are arranged, on the secondelectrode substrate, in the direction perpendicular to the stripestructure of the second electrodes 54 so that the whole of the effectivepicture elements are disposed between the two third electrodes as shownin FIG. 44. The top and bottom third electrodes 74 are connected,respectively, to third electrode withdrawal portions 75, 76 and thirdelectrode withdrawal portions 77, 78. As shown in FIG. 45, on the secondelectrodes 54, insulating layers 73 are formed so as to be perpendicularto the second electrodes 54. At the portion on which the third electrode74 is disposed, as shown in FIG. 46, the third electrode 74 is formed onthe insulating layer 73.

11TH EMBODIMENT

The 11th embodiment is an example of the arrangement in which thirdelectrodes 74 in a line form in the same number as that of the stripesof the second electrodes 54 are formed, on the second electrodesubstrate, in the direction parallel to the stripe structure of thesecond electrodes 54 between the stripes of the second electrodes 54 asshown in FIG. 47. The third electrodes 74 are individually connected tothird electrode withdrawal portions 75 and third electrode withdrawalportions 76. As shown in FIG. 48, on the second electrodes 54 and thethird electrodes 74, insulating layers 73 are formed so as to beperpendicular to the second electrodes 54 and third electrodes 74.

12TH EMBODIMENT

The 12th embodiment is an example of the arrangement in which thirdelectrodes 74 in a line form are formed, on the second electrodesubstrate, in the direction parallel to the stripe structure of thesecond electrodes 54 at intervals of the predetermined number of thestripes of the second electrodes 54 as shown in FIG. 49. The thirdelectrodes 74 are individually connected to third electrode withdrawalportions 75 and third electrode withdrawal portions 76. As shown in FIG.50, on the second electrodes 54 and the third electrodes 74, insulatinglayers 73 are formed so as to be perpendicular to the second electrodes54 and third electrodes 74.

Next, an example of the configuration of a passivematrix-electrodeposition type display device in which the thirdelectrode is disposed between the first transparent electrode and thesecond electrode is described.

13TH EMBODIMENT

In the 13th embodiment, as shown in FIG. 51, the device includestransparent picture element electrodes 52 formed in a stripe form on atransparent support 51, an electrolyte layer 55, and second electrodes54 which are formed in a stripe form on a support 53 facing thetransparent picture element electrodes. A third electrode 81 is disposedbetween the transparent picture element electrodes 52 and the secondelectrodes 54. The first transparent electrode side, i.e., transparentpicture element electrode 52 side has the configuration shown in FIG. 19and FIG. 20, and the second electrode side has the configuration shownin FIG. 37 and FIG. 38. As the third electrode 81, a twill type silvermesh having about 30-μm one side of the mesh structure is used, and thethird electrode 81 is sandwiched with nonwoven fabric 82 and disposedbetween the transparent picture element electrodes 52 and the secondelectrodes 54 so as to prevent the occurrence of short-circuitingbetween the third electrode and the other electrodes.

Next, examples of the configuration of an active matrix type,electrodeposition type display device in which the TFT for driving andfurther the third electrode are arranged on the side of the transparentpicture element electrode are described. In the following 14th to 20thembodiments, the basic configuration of the electrodeposition typedisplay device is the configuration of a conventional standard activematrix type, electrodeposition type display device in which no thirdelectrode is provided, i.e., configuration shown in FIG. 52 and FIG. 53.Specifically, the device includes transparent picture element electrodes92 as first transparent electrodes, which are formed on a transparentsupport 91 and controlled by TFTs 94 serving as driving devices, anelectrolyte layer 95, and a common electrode 96 as a second electrode,which is formed on a support 93 facing the transparent picture elementelectrodes 92, and which is common to the picture elements. Onetransparent picture element electrode 92 and one TFT 94 are combined toconstitute a picture element 99, and the picture elements are arrangedin a matrix form on the transparent support 91. FIG. 52 is across-sectional view of the electrodeposition type display device, andFIG. 53 is a plan view of FIG. 52, as viewed from the top.

As shown in FIG. 54, the transparent picture element electrodes 92 areconnected to transparent picture element electrode withdrawal portions97 and transparent picture element electrode withdrawal portions 98. Asshown in FIG. 55, an insulating layer 100 is formed between the pictureelements. FIG. 54 is a plan view of the transparent support 91, asviewed from the counter electrode side, and FIG. 55 is an enlarged viewof the essential portion indicated by an arrow T shown in FIG. 54.Hereinbelow, examples of the configuration of the third electrode aredescribed with reference to the plan view of the transparent support 91on which the transparent picture element electrodes 92 are formed(hereinafter, frequently referred to as “transparent picture elementelectrode substrate”), as viewed from the counter electrode side, andthe enlarged view of the essential portion with respect to eachembodiment.

14TH EMBODIMENT

The 14th embodiment is an example of the arrangement in which a thirdelectrode 101 in a line form is arranged on the transparent pictureelement electrode substrate so as to surround the whole of the effectivepicture elements on the side of the transparent picture elementelectrodes 92 as shown in FIG. 56. The third electrode 101 is connectedto third electrode withdrawal portions 102, 103, 104, 105. As shown inFIG. 57, an insulating layer 100 is formed between the picture elements.When the third electrode 101 is arranged so as to surround the whole ofthe effective picture elements as described above, the opening ratio canbe increased, making it possible to constitute an electrodeposition typedisplay device having preferable light withdrawal efficiency.

15TH EMBODIMENT

The 15th embodiment is an example of the arrangement in which top andbottom third electrodes 101 in a line form are arranged on thetransparent picture element electrode substrate so that the whole of theeffective picture elements on the side of the transparent pictureelement electrodes 92 are disposed between the two third electrodes 101as shown in FIG. 58. The top and bottom third electrodes 101 areconnected, respectively, to third electrode withdrawal portions 102, 103and third electrode withdrawal portions 104, 105. As shown in FIG. 59,an insulating layer 100 is formed between the picture elements. When thetop and bottom third electrodes 101 are arranged so that the whole ofthe effective picture elements are disposed between the two thirdelectrodes as described above, the opening ratio can be increased,making it possible to constitute an electrodeposition type displaydevice having preferable light withdrawal efficiency.

16TH EMBODIMENT

The 16th embodiment is an example of the arrangement in which thirdelectrodes 101 in a line form are arranged on the transparent pictureelement electrode substrate so that the two third electrodes 101 crossat the almost central portion of the whole of the effective pictureelements on the side of the transparent picture element electrodes 92 asshown in FIG. 60. The third electrodes 101 are connected to thirdelectrode withdrawal portions 102, 103, 104, 105. As shown in FIG. 61,an insulating layer 100 is formed between the picture elements.

17TH EMBODIMENT

The 17th embodiment is an example of the arrangement in which thirdelectrodes 101 are formed between all the picture element lines arrangedin the fixed direction on the plane of the effective picture elements onthe side of the transparent picture element electrodes as shown in FIGS.62 and 63. The third electrodes 101 are individually connected to thirdelectrode withdrawal portions 102, 103. As shown in FIG. 63, aninsulating layer 100 is formed between the picture elements.

18TH EMBODIMENT

The 18th embodiment is an example of the arrangement in which thirdelectrodes 101 are formed, on the plane of the effective pictureelements on the side of the transparent picture element electrodes,between the picture element lines arranged in the fixed direction atintervals of the predetermined number of lines, namely, a plurality ofpicture element lines as shown in FIGS. 64 and 65. The third electrodes101 are individually connected to third electrode withdrawal portions102, 103. As shown in FIG. 65, an insulating layer 100 is formed betweenthe picture elements.

19TH EMBODIMENT

The 19th embodiment is an example of the arrangement in which a thirdelectrode point 106 is formed per one picture element on the plane ofthe effective picture elements on the side of the transparent pictureelement electrodes as shown in FIGS. 66 and 67. The third electrodepoints 106 are connected to third electrode withdrawal portions 102, 103through not shown wiring. As shown in FIG. 67, an insulating layer 100is formed between the picture elements.

20TH EMBODIMENT

The 20th embodiment is an example of the arrangement in which a thirdelectrode point 106 is formed per predetermined plurality of pictureelements on the plane of the effective picture elements on the side ofthe transparent picture element electrodes as shown in FIGS. 68 and 69.The third electrode points 106 are connected to third electrodewithdrawal portions 102, 103 through not shown wiring. As shown in FIG.69, an insulating layer 100 is formed between the picture elements.

Next, examples of the configuration of an active matrix type,electrodeposition type display device in which the TFT for driving isdisposed on the side of the transparent picture element electrode andthe third electrode is arranged on the side of the second electrode as acounter electrode are described. In the following 21st to 25thembodiments, the basic configuration of the electrodeposition typedisplay device is substantially the same as that in the above 14th to20th embodiments except that the second electrodes are formed in astripe form and are not a common electrode, i.e., configuration shown inFIG. 70 and FIG. 71. Specifically, the device includes transparentpicture element electrodes 112 as first transparent electrodes, whichare formed on a transparent support 111 and controlled by TFTs 114serving as driving devices, an electrolyte layer 115, and secondelectrodes 116 which are formed on a support 113 facing the transparentpicture element electrodes 112. One transparent picture elementelectrode 112 and one TFT 114 are combined to constitute a pictureelement, and the picture elements are arranged in a matrix form on thetransparent support 111.

Hereinbelow, examples of the configuration of the third electrode aredescribed with reference to the plan view of the third electrodedisposed on the support 113 on which the second electrodes 116 areformed (hereinafter, frequently referred to as “second electrodesubstrate”), as viewed from the counter electrode side, and the enlargedview of the essential portion with respect to each embodiment.

21ST EMBODIMENT

The 21st embodiment is an example of the arrangement in which the secondelectrode substrate having the similar structure as that of the secondelectrode substrate in the above eighth embodiment is used, and a thirdelectrode 117 in a line form is arranged on the second electrodesubstrate so as to surround the whole of the effective picture elementson the side of the second electrodes 116 as shown in FIG. 72. Both endsof the second electrodes 116 are connected to second electrodewithdrawal portions 118, 119, and the third electrode 117 is connectedto third electrode withdrawal portions 120, 121, 122, 123.

22ND EMBODIMENT

The 22nd embodiment is an example of the arrangement in which the secondelectrode substrate having the similar structure as that of the secondelectrode substrate in the above ninth embodiment is used, and right andleft third electrodes 117 in a line form are arranged on the secondelectrode substrate so that the whole of the effective picture elementson the side of the second electrodes 116 are disposed between the rightand left third electrodes 117 as shown in FIG. 73. Both ends of thesecond electrodes 116 are connected to second electrode withdrawalportions 118, 119, and the third electrodes 117 are connected to thirdelectrode withdrawal portions 120, 121, 122, 123.

23RD EMBODIMENT

The 23rd embodiment is an example of the arrangement in which the secondelectrode substrate having the similar structure as that of the secondelectrode substrate in the above 10th embodiment is used, and top andbottom third electrodes 117 in a line form are arranged on the secondelectrode substrate so that the whole of the effective picture elementson the side of the second electrodes 116 are disposed between the topand bottom third electrodes 117 as shown in FIG. 74. Both ends of thesecond electrodes 116 are connected to second electrode withdrawalportions 118, 119, and the third electrodes 117 are connected to thirdelectrode withdrawal portions 120, 121, 122, 123.

24TH EMBODIMENT

The 24th embodiment is an example of the arrangement in which the secondelectrode substrate in the above 11th embodiment is used as the secondelectrode substrate, and third electrodes 117 in a line form in the samenumber as that of the stripes of the second electrodes 116 are formed,on the second electrode substrate, in the direction parallel to thestripe structure of the second electrodes 116 between the stripes of thesecond electrodes 116 as shown in FIGS. 75 and 76. Both ends of thesecond electrodes 116 are connected to second electrode withdrawalportions 118, 119, and the third electrodes 117 are connected to thirdelectrode withdrawal portions 120, 121. As shown in FIG. 76, on thesecond electrodes 116 and the third electrodes 117, insulating layers124 are formed so as to be perpendicular to the second electrodes 116and third electrodes 117.

25TH EMBODIMENT

The 25th embodiment is an example of the arrangement in which the secondelectrode substrate in the above 12th embodiment is used as the secondelectrode substrate, and third electrodes 117 in a line form are formed,on the second electrode substrate, in the direction parallel to thestripe structure of the second electrodes 116 at intervals of thepredetermined number of the stripes of the second electrodes 116 asshown in FIGS. 77 and 78. Both ends of the second electrodes 116 areconnected to second electrode withdrawal portions 118, 119, and thethird electrodes 117 are connected to third electrode withdrawalportions 120, 121. As shown in FIG. 78, on the second electrodes 116 andthe third electrodes 117, insulating layers 124 are formed so as to beperpendicular to the second electrodes 116 and third electrodes 117.

Next, examples of the configuration of an active matrix type,electrodeposition type display device in which the third electrode isdisposed between the first transparent electrode and the secondelectrode are described.

26TH EMBODIMENT

In the 26th embodiment, as shown in FIG. 79, the device includestransparent picture element electrodes 132 as first transparentelectrodes, which are formed on a transparent support 131 and controlledby TFTs 134 serving as driving devices, an electrolyte layer 135, and asecond electrode 136 comprised of an Ag substrate, which is formed on asupport 133 facing the transparent picture element electrodes 132. Thetransparent picture element substrate has the above-described structureshown in FIGS. 54 and 55, and picture elements, each formed by combiningone transparent picture element electrode 132 and one TFT 134, arearranged in a matrix form on the transparent support 131.

A third electrode 137 is disposed between the transparent pictureelement electrodes 132 and the second electrode 136. As the thirdelectrode 137, a twill type Ag mesh having about 30-μm one side of themesh structure is used, and the third electrode 137 is sandwiched withnonwoven fabric 138 and disposed between the transparent picture elementelectrodes 132 and the second electrode 136 so as to prevent theoccurrence of short-circuiting between the third electrode and the otherelectrodes.

27TH EMBODIMENT

In the 27th embodiment, as shown in FIG. 80, the device includestransparent picture element electrodes 132 as first transparentelectrodes formed on a transparent support 131, an electrolyte layer135, and second electrodes 136, which are formed on a support 133 facingthe transparent picture element electrodes 132, and controlled by TFTs134 serving as driving devices. One second electrode 136 and one TFT 134are combined to constitute a picture element, and the picture elementsare arranged in a matrix form on the support 133.

A third electrode 137 is disposed between the transparent pictureelement electrodes 132 and the second electrodes 136. As the thirdelectrode 137, a twill type Ag mesh having about 30-μm one side of themesh structure is used, and the third electrode 137 is sandwiched withnonwoven fabric 138 and disposed between the transparent picture elementelectrodes 132 and the second electrodes 136 so as to prevent theoccurrence of short-circuiting between the third electrode and the otherelectrodes.

Next, examples of the configuration of an active matrix type,electrodeposition type display device in which the TFT for driving isdisposed on the side of the second electrode and the third electrode isarranged on the side of the transparent picture element electrode aredescribed. In the following 28th to 34th embodiments, as shown in FIG.81, the basic electrodeposition type display device includes secondelectrodes 146 comprised of a metallic thin film, which are formed on asupport 143 and controlled by TFTs 144 serving as driving devices, anelectrolyte layer 145, and first transparent picture element electrodes142 opposite to the second electrodes 146. The first transparent pictureelement electrodes 142 are formed in a stripe form on a transparentsupport 141. The electrolyte layer 145 is comprised of an electrolyticsolution or a polymer electrolyte, which contain metal ions and acoloring agent, and the gap portion between the first transparentpicture element electrodes 142 and the second electrodes 146 is filledwith the electrolyte layer 145.

28TH EMBODIMENT

The 28th embodiment is an example of the arrangement in which a thirdelectrode 147 in a line form is formed on the transparent pictureelement electrode substrate so as to surround the whole of the effectivepicture elements on the side of the transparent picture elementelectrodes 142 as shown in FIG. 82. Both ends of the transparent pictureelement electrodes 142 are connected to transparent picture elementelectrode withdrawal portions 148, 149, and the third electrode 147 isconnected to third electrode withdrawal portions 150, 151, 152, 153. Asshown in FIG. 83, on the transparent picture element electrodes 142,insulating layers 154 are formed so as to be perpendicular to thetransparent picture element electrodes 142. At the portion on which thethird electrode 147 is disposed, as shown in FIG. 84, the thirdelectrode 147 is formed on the insulating layer 154. When the thirdelectrode is arranged so as to surround the whole of the effectivepicture elements as described above, the opening ratio can be increased,making it possible to constitute an electrodeposition type displaydevice having preferable light withdrawal efficiency.

29TH EMBODIMENT

The 29th embodiment is an example of the arrangement in which right andleft third electrodes 147 in a line form are formed, on the transparentpicture element electrode substrate, in the direction parallel to thestripe structure of the transparent picture element electrodes 142 sothat the whole of the effective picture elements are disposed betweenthe right and left third electrodes 147 as shown in FIG. 85. Both endsof the transparent picture element electrodes 142 are connected totransparent picture element electrode withdrawal portions 148, 149, andthe right and left third electrodes 147 are connected, respectively, tothird electrode withdrawal portions 150, 153 and third electrodewithdrawal portions 151, 152. As shown in FIG. 86, on the transparentpicture element electrodes 142, insulating layers 154 are formed so asto be perpendicular to the transparent picture element electrodes 142.

30TH EMBODIMENT

The 30th embodiment is an example of the arrangement in which top andbottom third electrodes 147 in a line form are formed, on thetransparent picture element electrode, in the direction perpendicular tothe stripe structure of the transparent picture element electrodes 142so that the whole of the effective picture elements are disposed betweenthe top and bottom third electrodes 147 as shown in FIG. 87. Both endsof the transparent picture element electrodes 142 are connected totransparent picture element electrode withdrawal portions 148, 149, andthe top and bottom third electrodes 147 are connected, respectively, tothird electrode withdrawal portions 150, 151 and third electrodewithdrawal portions 152, 153. As shown in FIG. 88, on the transparentpicture element electrodes 142, insulating layers 154 are formed so asto be perpendicular to the transparent picture element electrodes 142.At the portion on which the third electrode 147 is disposed, as shown inFIG. 89, the third electrode 147 is formed on the insulating layer 154.

31ST EMBODIMENT

The 31st embodiment is an example of the arrangement in which thirdelectrodes 147 in a line form in the same number as that of the stripesof the transparent picture element electrodes 142 are formed in thedirection parallel to the stripe structure of the transparent pictureelement electrodes 142 between the stripes of the transparent pictureelement electrodes 142 as shown in FIG. 90. Both ends of the transparentpicture element electrodes 142 are connected to transparent pictureelement electrode withdrawal portions 148, 149, and the third electrodes147 are individually connected to third electrode withdrawal portions150 and third electrode withdrawal portions 151. As shown in FIG. 91, onthe transparent picture element electrodes 142 and the third electrodes147, insulating layers 154 are formed so as to be perpendicular to thetransparent picture element electrodes 142 and third electrodes 147.

32ND EMBODIMENT

The 32nd embodiment is an example of the arrangement in which thirdelectrodes 147 in a line form are formed in the direction parallel tothe stripe structure of the transparent picture element electrodes 142at intervals of the predetermined number of the stripes of thetransparent picture element electrodes 142 as shown in FIG. 92. Bothends of the transparent picture element electrodes 142 a reconnected totransparent picture element electrode withdrawal portions 148, 149, andthe third electrodes 147 are individually connected to third electrodewithdrawal portions 150 and third electrode withdrawal portions 151. Asshown in FIG. 93, on the transparent picture element electrodes 142 andthe third electrodes 147, insulating layers 154 are formed so as to beperpendicular to the transparent picture element electrodes 142 andthird electrodes 147.

In the present invention, with respect to the configuration of thetransparent picture element electrode, second electrode, and thirdelectrode, a configuration may be employed in which only electrode linesare formed and no insulating layer is provided. Specifically, there maybe employed a configuration shown in, for example, FIG. 94 in which onlythird electrodes 163 are formed in parallel to transparent pictureelement electrodes 162 on a transparent support 161, and no insulatinglayer is provided.

Alternatively, a configuration in which insulating layers are providedon electrode lines by patterning in the direction perpendicular to theelectrode lines may be employed. Specifically, there can be employed aconfiguration shown in, for example, FIG. 95 in which third electrodes163 are formed in parallel to transparent picture element electrodes 162on a transparent support 161, and further, on the transparent pictureelement electrodes 162 and the third electrodes 163, insulating layers164 are formed by patterning in the direction perpendicular to them. Byemploying this configuration, picture elements can be formed by theinsulating layers 164.

Further alternatively, a configuration in which insulating layers areformed by patterning so as to expose only the picture element portionand the third electrode portion may be employed. Specifically, there canbe employed a configuration shown in, for example, FIG. 96 in whichthird electrodes 163 are formed in parallel to transparent pictureelement electrodes 162 on a transparent support 161, and insulatinglayers 164 are formed in parallel to the gap between the transparentpicture element electrodes 162 and the third electrodes 163, andpatterned so as to cover the transparent picture element electrodes 161excluding corresponding portions of the third electrodes 162. Byemploying this configuration, picture elements can be formed by theinsulating layers 164 while protecting the transparent electrodes.

Here, an explanation is made on the transparent picture elementelectrode substrate, but the similar configuration can be applied to thesecond electrode substrate.

EXAMPLES

Hereinbelow, the present invention will be described in more detail withreference to the following specific Examples. The following Examplesshould not be construed as limiting the scope of the present invention.

Example 1

(Preparation of Display Electrode)

First, on a glass substrate having a thickness of 1.5 mm and a size of10 cm×10 cm, as transparent picture element electrodes 201, ITO filmsarranged in a line form at a pitch of 150 μm were formed by a knownmethod. Then, one third electrode 202 was formed at the central portionof the lines of the ITO films so as to be parallel to the lines. Thethird electrode 202 was formed using Ag to have a width of 1 μm. Then,effective picture element portions and their periphery portions werecoated and patterned to form insulating layers 203 perpendicular to thelines of the ITO films. Subsequently, lead portions connected from thesubstrate to driving circuits were formed by a known method, to connectthe transparent picture element electrodes 201 to transparent pictureelement electrode withdrawal portions 204, 205, and connect the thirdelectrode 202 to third electrode withdrawal portions 206, 207, thuspreparing display electrodes shown in FIGS. 97 and 98.

(Preparation of Counter Electrode)

On a glass substrate having a thickness of 1.5 mm and a size of 8 cm×12cm, a Cr film was vapor-deposited by a known method, and Ag films havinga thickness of 1,000 nm arranged in a line form at a pitch of 150 μmwere formed on the Cr film by a known method. Then, effective pictureelement portions and their periphery portions were patterned to forminsulating layers on the ITO films perpendicular to the lines of the ITOfilms, thus preparing counter electrodes.

(Preparation of Polymer Electrolyte Layer)

1 Part by weight of polyether having a molecular weight of about350,000, 10 parts by weight of dimethylformamide (DMSO), 1.7 part byweight of sodium iodide, and 1.7 part by weight of silver iodide weremixed with one another, and heated to 120° C. to prepare a uniformsolution. Then, to the uniform solution were added triethanolaminerepresented by the chemical formula 5 below, coumarin represented by thechemical formula 6 below, and benzimidazole represented by the chemicalformula 7 below so that the respective concentrations became 10 g/l, 5g/l, and 5 g/l.

Then, 0.2 part by weight of titanium dioxide having an average particlesize of 0.5 μm was added to the resultant mixture, and uniformlydispersed together by means of a homogenizer. The resultant dispersedmixture was applied by means of a doctor blade onto the glass substrateof the above-prepared display electrodes so that the thickness became100 μm, and then immediately the counter electrodes as the secondelectrodes were attached on the substrate to form a gelled polymerelectrolyte between the two electrodes. Then, the edges of the resultantlaminate were sealed with an adhesive, thus preparing a passivematrix-electrodeposition type display apparatus in Example 1.

(Evaluation of Driving and Display Properties)

A reduction reaction was caused on the display electrode side at anelectrical quantity of 10 mC/cm² per one picture element duringcoloring, and oxidation was caused at the same electrical quantityduring decoloring by means of a known passive matrix driving circuit toswitch colored display and colorless (white) display. In the driving,the input waveform controlled may be either current or voltage.

For confirming effectiveness of the third electrode as a referenceelectrode, with respect to the selected transparent picture elementelectrodes having different distances from the third electrode, cyclicvoltammogram measurements were conducted per predetermined pictureelements. The cyclic voltammogram measurements were conducted withrespect to the counter electrode picture element line A (35 mm from thecenter of the effective picture element portion) and the counterelectrode picture element line B (5 mm from the center of the effectivepicture element portion), and, in each case, measurements were conductedwith respect to the distances from the third electrode of 50 μm, 500 μm,2 mm, 10 mm, and 40 mm. As the input waveform, a voltage triangular waveat 50 mV/sec was applied in the range of from −1.0 to −1.5 V on thereduction side and in the range of from +1.0 to +1.4 V on the oxidationside, relative to the potential of Ag as a reference electrode of thethird electrode. The results with respect to the counter electrodepicture element line A are shown in FIG. 99, and the results withrespect to the counter electrode picture element line B are shown inFIG. 100.

As can be seen in FIGS. 99 and 100, substantially similar results wereobtained with respect to all the transparent picture element electrodesfrom the transparent picture element electrode immediately adjacent tothe third electrode to the farthest one. Generally, it is preferred thatthe transparent picture element electrode which is a working electrodeand the third electrode are as close as possible, but the results ofFIGS. 99 and 100 have confirmed that the third electrode effectivelyoperates almost irrespective of the distance between the third electrodeand the transparent picture element electrode as a working electrode.

Specifically, for achieving arrangement such that the third electrodemore effectively operates to obtain higher reliability, it is preferredthat the third electrodes in the same number as that of the stripes ofthe transparent picture element electrodes are disposed between thestripes of the transparent picture element electrodes. However,considering the opening ratio on the side of the transparent pictureelement electrodes and the trade-off, the structure in the presentExample in which one third electrode in a line form is disposed at thecentral portion of the effective picture element portion has no problem,and is considered to make it possible to effectively operate the thirdelectrode and effectively utilize the effect.

In addition, from the above results, it is found that, in the drivingaccording to a linear successive method or the like as a method forpicture element display, there is no need to provide the third electrodeseparately, and part of the counter electrodes which are not selectedand are inactive as electrical signals can serve as a quasi-thirdelectrode.

Example 2

(Preparation of Display Electrode)

First, on a glass substrate having a thickness of 1.5 mm and a size of10 cm×10 cm, as transparent picture element electrodes, ITO films andTFTs (thin film transistors) arranged in a plane form at a pitch of 150μm were prepared by a known method to form picture element portions 211.Then, third electrodes 212 were disposed so that the two thirdelectrodes crossed each other at the almost central portion of theeffective picture element portions. The third electrodes 212 were formedusing silver to have a width of 1 μm. Then, effective picture elementportions and their periphery portions, excluding the picture elementportions 211 and third electrodes 212, were coated and patterned to forminsulating layers 213 perpendicular to the picture element lines of theITO films. Lead portions connected from the substrate to drivingcircuits were formed by a known method, to connect the picture elementportions 211 to transparent picture element electrode withdrawalportions 214, 215, and connect the third electrodes 212 to thirdelectrode withdrawal portions 216, 217, 218, 219, thus preparing displayelectrodes shown in FIGS. 101 and 102.

(Preparation of Counter Electrode)

On a glass substrate having a thickness of 1.5 mm and a size of 8 cm×12cm, a Cr film was vapor-deposited by a known method, and an Ag alloythin film having a thickness of 1,000 nm was formed on the Cr film by aknown method, thus preparing counter electrodes.

(Preparation of Polymer Electrolyte Layer)

A polymer electrolyte was prepared in the same manner as in Example 1above, and applied by means of a doctor blade onto the glass substrateof the above-prepared display electrodes so that the thickness became100 μm, and then immediately the counter electrodes as the secondelectrodes were attached on the glass substrate to form a gelled polymerelectrolyte between the two electrodes. Then, the edges of the resultantlaminate were sealed with an adhesive, thus preparing an active matrixtype, electrodeposition type display apparatus in Example 2.

(Evaluation of Driving and Display Properties)

With respect to the counter electrode picture element line A (35 mm fromthe center of the effective picture element portion) and the counterelectrode picture element line B (5 mm from the center of the effectivepicture element portion), cyclic voltammogram measurements wereconducted per predetermined picture elements with respect to theselected transparent picture element electrodes having differentdistances from the third electrode in the same manner as in Example 1.The results with respect to the counter electrode picture element line Aare shown in FIG. 103, and the results with respect to the counterelectrode picture element line B are shown in FIG. 104.

As can be seen in FIGS. 103 and 104, substantially similar results wereobtained with respect to all the transparent picture element electrodesfrom the transparent picture element electrode immediately adjacent tothe third electrode to the farthest one. Generally, it is preferred thatthe transparent picture element electrode which is a working electrodeand the third electrode are as close as possible, but, from the resultsof FIGS. 103 and 104, it has been found that the third electrodeeffectively operates almost irrespective of the distance between thethird electrode and the transparent picture element electrode as aworking electrode.

Specifically, for achieving arrangement such that the third electrodemore effectively operates to obtain higher reliability, it is preferredthat the third electrode is disposed per picture element portion.However, considering the opening ratio on the side of the transparentpicture element electrodes and the trade-off, the structure in thepresent Example in which the two third electrodes cross at the almostcentral portion of the effective picture element portions has noproblem, and is considered to make it possible to effectively operatethe third electrode and effectively utilize the effect.

Example 3

(Preparation of Display Electrode)

Display electrodes were prepared in substantially the same manner as inExample 1 except that no third electrode was formed.

(Preparation of Counter Electrode)

Counter electrodes shown in FIGS. 105 and 106 were prepared insubstantially the same manner as in Example 1 above except that thethird electrode was formed from Ag to have a width of 1 μm only at thecentral portion of the effective picture element portions. Specifically,one third electrode 222 was disposed in parallel to the secondelectrodes 221 arranged in a line form at the central portion of theeffective picture element portions, and the second electrodes 221 wereconnected to second electrode withdrawal portions 224, 225 and the thirdelectrode 222 was connected to third electrode withdrawal portions 226,227. The effective picture element portions and their periphery portionswere patterned to form insulating layers 223 on the ITO filmsperpendicular to the lines of the ITO films.

(Preparation of Polymer Electrolyte Layer)

A polymer electrolyte was prepared in the same manner as in Example 1above, and applied by means of a doctor blade onto the glass substrateof the above-prepared display electrodes so that the thickness became100 μm, and then immediately the counter electrodes as the secondelectrodes were attached on the substrate to form a gelled polymerelectrolyte between the two electrodes. Then, the edges of the resultantlaminate were sealed with an adhesive, thus preparing a passivematrix-electrodeposition type display apparatus in Example 3.

(Evaluation of Driving and Display Properties)

With respect to the counter electrode picture element line A (35 mm fromthe center of the effective picture element portion) and the counterelectrode picture element line B (5 mm from the center of the effectivepicture element portion), cyclic voltammogram measurements wereconducted per predetermined picture elements with respect to theselected transparent picture element electrodes having differentdistances from the third electrode in the same manner as in Example 1.The results with respect to the counter electrode picture element line Aare shown in FIG. 107, and the results with respect to the counterelectrode picture element line B are shown in FIG. 108.

As can be seen in FIGS. 107 and 108, substantially similar results wereobtained with respect to all the transparent picture element electrodesfrom the transparent picture element electrode immediately adjacent tothe third electrode to the farthest one. Generally, it is preferred thatthe transparent picture element electrode which is a working electrodeand the third electrode are as close as possible, and they are close inrespect of the width direction and on the same plane if possible.However, from the results of FIGS. 107 and 108, it has been found thatthe third electrode effectively operates, almost irrespective of thedistance between the third electrode and the transparent picture elementelectrode as a working electrode, even when the third electrode isdisposed on the counter electrode side.

Specifically, for achieving arrangement such that the third electrodemore effectively operates to obtain higher reliability, the structure inExample 1 above is preferred, but the structure in the present Examplein which the third electrode is not disposed on the side of thetransparent picture element electrodes has no particular problem, andthe highest opening ratio on the side of the transparent picture elementelectrodes can be advantageously secured.

Example 4

(Preparation of Electrodeposition Type Display Apparatus)

A passive matrix-electrodeposition type display apparatus was preparedin substantially the same manner as in Example 1 except that the thirdelectrode was formed from an ITO instead of Ag.

(Evaluation of Driving and Display Properties)

With respect to the counter electrode picture element line A (35 mm fromthe center of the effective picture element portion), cyclicvoltammogram measurements were conducted per predetermined pictureelements with respect to the selected transparent picture elementelectrodes having different distances from the third electrode in thesame manner as in Example 1. The results are shown in FIG. 109.

As can be seen in FIG. 109, results were obtained such that the whole ofthe measurements shifted according to the distance between the thirdelectrode and the transparent picture element electrode immediatelyadjacent to the third electrode to the farthest transparent pictureelement electrode. From this, it has been found that the effect of thethird electrode depends on the distance between the third electrode andthe transparent picture element electrode which is a working electrode,and the third electrode does not effectively operate. However, bycorrecting the shifted amount at the individual distance per eachpicture element line, the third electrode can effectively operate likein Example 1 above. Alternatively, by increasing the number of the thirdelectrodes, the third electrode can effectively operate like in Example1 above. For simplifying the configuration of the driving circuit,however, the configuration in Example 1 is preferred.

Example 5

With respect to the active matrix type, electrodeposition type displayapparatus prepared in Example 2, an actual display waveform was appliedin the same manner as in Example 1 to repeat a cycle of coloring anddecoloring. In addition, with respect to the apparatus in which thethird electrode was not effective, namely, no third electrode wasprovided, a waveform was applied to two electrodes, i.e., the displayelectrode and the counter electrode to repeat a cycle of coloring anddecoloring in the same manner. The results of above two were compared toeach other. The electrodeposition type display apparatus had initialproperties such that the reflectance during colorless (white) was 70%and the optical density (OD) of the display portion during coloring(black) was about 0.8 (reflectance: 13%). Accordingly, the contrast ofreflectance obtained was 1:5.

In the apparatus for comparison which had no effective third electrodeand operated in a dual electrode mode, the repetition of the cyclesuntil the black density during coloring became 1.0 or less was about80,000,000, whereas, in the apparatus in which the third electrode waseffective, the black density was not lowered to be 1.0 or less evenafter repetition of the double cycles of the above, and further aphenomenon in which the color remained upon decoloring did not occur.This result indicates that the use of the third electrode canconsiderably improve the cycle properties, as compared to a conventionalapparatus having no third electrode. Further, the use of the thirdelectrode can appropriately control the display switching, as comparedto a conventional apparatus having no third electrode. That is, the useof the third electrode can realize an electrodeposition type displayapparatus having preferable cycle properties and preferable displayquality.

Example 6

Using the display electrodes prepared in Example 3 in which no thirdelectrode was formed and the counter electrodes prepared in Example 1 inwhich no third electrode was formed, and using a twill type silver meshhaving about 30-μm one side of the mesh structure as a third electrode,the third electrode was sandwiched with nonwoven fabric and disposedbetween the display electrodes and the counter electrodes so as toprevent the occurrence of short-circuiting between the third electrodeand the other electrodes, thereby preparing an electrodeposition typedisplay apparatus. A polymer electrolyte layer was formed in the samemanner as in Example 1.

With respect to the thus-prepared passive matrix-electrodeposition typedisplay apparatus in Example 6, cyclic voltammogram measurements wereconducted in the same manner as in Example 1. As a result, there wereobtained results substantially similar to those obtained in Example 1.This has confirmed that, in the passive matrix-electrodeposition typedisplay apparatus in which the third electrode having a mesh structureis disposed between the display electrodes and the counter electrodes,the third electrode effectively operates, and thus effectiveness of theuse of the third electrode is confirmed.

Example 7

Display electrodes were prepared in substantially the same manner as inExample 2 except that no third electrode was formed, and, on a glasssubstrate having a thickness of 1.5 mm and a size of 8 cm×12 cm, nothird electrode was formed, and second electrodes having a stripestructure were formed from an Ag thin film by a known method to preparecounter electrodes. Lead portions connected from these substrates todriving circuits were formed by a known method. Then, as a thirdelectrode, a twill type silver mesh having about 30-μm one side of themesh structure was used, and the third electrode was sandwiched withnonwoven fabric and disposed between the display electrodes and thecounter electrodes so as to prevent the occurrence of short-circuitingbetween the third electrode and the other electrodes, thereby preparingan active matrix type, electrodeposition type display apparatus. Apolymer electrolyte layer was formed in the same manner as in Example 1.

With respect to the thus-prepared electrodeposition type displayapparatus in Example 7, cyclic voltammogram measurements were conductedin the same manner as in Example 2. As a result, there were obtainedresults substantially similar to those obtained in Example 2. This hasconfirmed that, in the active matrix type, electrodeposition typedisplay apparatus in which the third electrode having a mesh structureis disposed between the display electrodes and the counter electrodes,the third electrode effectively operates, and thus effectiveness of theuse of the third electrode is confirmed.

Example 8

(Preparation of Display Electrode)

First, on a glass substrate having a thickness of 1.5 mm and a size of10 cm×10 cm, as transparent picture element electrodes, ITO films wereformed by a known method to prepare display electrodes.

(Preparation of Counter Electrode)

On a glass substrate having a thickness of 1.5 mm and a size of 8 cm×12cm, Ag alloy films and TFTs (thin film transistors) arranged in a planeform at a pitch of 150 μm were prepared by a known method to formpicture elements. Then, third electrodes were disposed so that the twothird electrodes crossed each other at the almost central portion of theeffective picture element portions to prepare counter electrodes. Thethird electrodes were formed using silver to have a width of 1 μm. Then,an active matrix type, electrodeposition type display apparatus wasprepared in the same manner as in Example 2.

With respect to the thus-prepared electrodeposition type displayapparatus in Example 8, cyclic voltammogram measurements were conductedin the same manner as in Example 2. As a result, there were obtainedresults substantially similar to those obtained in Example 2, andsubstantially similar results were obtained with respect to all thedevice electrodes from the device electrode immediately adjacent to thethird electrode to the farthest one. Generally, it is preferred that thetransparent picture element electrode which is a working electrode andthe third electrode are as close as possible, but, from the aboveresults, it has been found that the third electrode effectivelyoperates, almost irrespective of the distance between the thirdelectrode and the transparent picture element electrode as a workingelectrode, even when the third electrode is disposed on the counterelectrode side as in the present Example.

Example 9

(Preparation of Display Electrode)

Fist, on a glass substrate having a thickness of 1.5 mm and a size of 10cm×10 cm, as transparent picture element electrodes, ITO films arrangedin a line form at a pitch of 150 82 m were formed by a known method.Then, one third electrode was formed at the central portion of the linesof the ITO films so as to be parallel to the lines. The third electrodewas formed using Ag to have a width of 1 μm. Then, effective pictureelement portions and their periphery portions were coated and patternedto form insulating layers perpendicular to the lines of the ITO films.Subsequently, lead portions connected from the substrate to drivingcircuits were formed by a known method, thus preparing displayelectrodes.

(Preparation of Counter Electrode)

Counter electrodes were prepared in substantially the same manner as inExample 8 except that no third electrode was formed. Then, an activematrix type, electrodeposition type display apparatus was prepared inthe same manner as in Example 2.

With respect to the thus-prepared electrodeposition type displayapparatus in Example 9, cyclic voltammogram measurements were conductedin the same manner as in Example 2. As a result, there were obtainedresults substantially similar to those obtained in Example 2, andsubstantially similar results were obtained with respect to all thedevice electrodes from the device electrode immediately adjacent to thethird electrode to the farthest one. Generally, it is preferred that thetransparent picture element electrode which is a working electrode andthe third electrode are as close as possible, but the above results haveconfirmed that the third electrode effectively operates almostirrespective of the distance between the third electrode and thetransparent picture element electrode serving as a working electrode.

Industrial Applicability

The electrochemical display device and electrochemical display apparatusaccording to the present invention can achieve matrix driving perpicture element, and utilize the coloring material and coloring meanscontained in the electrolyte layer, and further have a third electrodeindependent of the first transparent electrode and the second electrode.

Therefore, according to the electrochemical display device andelectrochemical display apparatus of the present invention, there can beprovided an electrodeposition type display device and anelectrodeposition type display apparatus having preferable cycleproperties and preferable display quality such that display with highcontrast and high black density can be achieved.

In addition, by the method for producing an electrochemical displaydevice and the method for producing an electrochemical display apparatusaccording to the present invention, an electrochemical display deviceand an electrochemical display apparatus having the above-describedstructure can be easily produced.

1. An electrochemical display device characterized by comprising: afirst transparent electrode; an electrolyte layer containing a coloringmaterial which colors by a coloring means and electrochemical reductionor oxidation, accompanied by deposition or dissolution; a secondelectrode having said electrolyte layer disposed between said firsttransparent electrode and said second electrode; and a third electrodeindependent of said first transparent electrode and said secondelectrode.
 2. The electrochemical display device according to claim 1,characterized in that said third electrode is provided as anelectrically insulated member on a substrate on which said firsttransparent electrode is formed.
 3. The electrochemical display deviceaccording to claim 1, characterized in that said third electrode isprovided as an electrically insulated member on a substrate on whichsaid second electrode is formed.
 4. The electrochemical display deviceaccording to claim 1, characterized in that said third electrode isprovided as an electrically insulated member between said firsttransparent electrode and said second electrode.
 5. The electrochemicaldisplay device according to claim 4, characterized in that said thirdelectrode is comprised of a metal wire or a mesh structure obtained byweaving said metal wire.
 6. The electrochemical display device accordingto claim 5, characterized in that said third electrode is disposedbetween insulating materials.
 7. The electrochemical display deviceaccording to claim 1, characterized in that said third electrode isprovided in a state in which said third electrode surrounds an effectivepicture element portion of said first transparent electrode or saidsecond electrode.
 8. The electrochemical display device according toclaim 1, characterized in that said third electrode is provided in astate in which said third electrode sandwiches an effective pictureelement portion of said first transparent electrode or said secondelectrode.
 9. The electrochemical display device according to claim 1,characterized in that a plurality of said third electrodes are providedin a state in which a plurality of said third electrodes cross oneanother in an effective picture element portion of said firsttransparent electrode or said second electrode.
 10. The electrochemicaldisplay device according to claim 1, characterized in that said firsttransparent electrode is included mainly of SnO₂, In₂O₃, or a mixturethereof.
 11. The electrochemical display device according to claim 1,characterized in that said second electrode is a metallic thin film. 12.The electrochemical display device according to claim 1, characterizedin that said third electrode is a metallic thin film.
 13. Theelectrochemical display device according to claim 1, characterized inthat said third electrode is a transparent electrode included mainly ofSnO₂, In₂O₃, or a mixture thereof.
 14. The electrochemical displaydevice according to claim 1, characterized in that said third electrodeis part of said first transparent electrode or said second electrode,which is in a display inactive state.
 15. The electrochemical displaydevice according to claim 1, characterized in that said electrolytelayer is d of an electrolytic solution or a polymer electrolyte layer.16. The electrochemical display device according to claim 15,characterized in that said electrolytic solution or polymer electrolytelayer contains a metal salt or a quaternary alkylammonium salt.
 17. Theelectrochemical display device according to claim 15, characterized inthat a solvent for said electrolytic solution is comprised of water,ethyl alcohol, isopropyl alcohol, propylene carbonate, dimethylcarbonate, ethylene carbonate, γ-butyrolactone, acetonitrile, sulfolane,dimethoxyethane, dimethylformamide, dimethyl sulfoxide, or a mixturethereof.
 18. The electrochemical display device according to claim 15,characterized in that a matrix polymer constituting said polymerelectrolyte layer is a polymer material having a repeating unit ofalkylene oxide, alkylenimine, or alkylene sulfide in a main skeletonunit or a side chain unit, or both of them; a copolymer including aplurality of these different units; or a polymethyl methacrylatederivative; polyvinylidene fluoride; polyvinylidene chloride;polyacrylonitrile; a polycarbonate derivative; or a mixture or laminatethereof.
 19. The electrochemical display device according to claim 18,characterized in that said polymer electrolyte layer includes saidmatrix polymer containing a solvent which is comprised of water, ethylalcohol, isopropyl alcohol, propylene carbonate, dimethyl carbonate,ethylene carbonate, γ-butyrolactone, acetonitrile, sulfolane,dimethoxyethane, dimethylformamide, dimethyl sulfoxide, or a mixturethereof.
 20. The electrochemical display device according to claim 15,characterized in that said polymer electrolyte layer is comprised of aplurality of layers, wherein said coloring means is contained in part ofthe layers.
 21. The electrochemical display device according to claim 1,characterized in that said electrolyte layer contains at least onemember selected from a growth inhibitor, a stress relaxing agent, and abrightener for the deposition of said coloring material.
 22. Theelectrochemical display device according to claim 21, characterized inthat said growth inhibitor, stress relaxing agent, or brightener is anorganic compound having a group having an oxygen atom or a sulfur atom.23. The electrochemical display device according to claim 1,characterized in that said electrolyte layer contains a reducing agentor an oxidizing agent for suppressing a side reaction which is possiblycaused in any of said first transparent electrode and said secondelectrode mainly due to an anion species during the deposition of saidcoloring material.
 24. The electrochemical display device according toclaim 1, characterized in that said coloring material is ions ofbismuth, copper, silver, sodium, lithium, iron, chromium, nickel, orcadmium, or ions comprised of a combination thereof.
 25. Theelectrochemical display device according to claim 1, characterized inthat said coloring means is an inorganic pigment or an organic pigment,or a dye.
 26. The electrochemical display device according to claim 25,characterized in that said inorganic pigment is comprised of powder oftitanium dioxide, calcium carbonate, magnesium oxide, or aluminum oxide.27. The electrochemical display device according to claim 1,characterized in that said electrochemical display device is driven bydetecting or sweeping a potential between said third electrode and saidfirst transparent electrode.
 28. The electrochemical display deviceaccording to claim 1, characterized in that said electrochemical displaydevice has a driving device in said first transparent electrode or saidsecond electrode and said driving device is driven in an active matrixmode.
 29. The electrochemical display device according to claim 1,characterized in that said first transparent electrode and said secondelectrode are arranged in a matrix form, and said device is driven in apassive matrix mode.
 30. An electrochemical display apparatuscharacterized by comprising a plurality of electrochemical displaydevices arranged in a plane form, each electrochemical display devicehaving: a first transparent electrode; an electrolyte layer containing acoloring material which colors by a coloring means and electrochemicalreduction or oxidation, accompanied by deposition or dissolution; asecond electrode having said electrolyte layer disposed between saidfirst transparent electrode and said second electrode; and a thirdelectrode independent of said first transparent electrode and saidsecond electrode.
 31. A method for producing an electrochemical displaydevice, characterized by comprising the steps of: forming a firsttransparent electrode on a transparent support; forming an electrolytelayer containing a coloring material which colors by a coloring meansand electrochemical reduction or oxidation, accompanied by deposition ordissolution; forming a second electrode having said electrolyte layerdisposed between said first transparent electrode and said secondelectrode; and forming a third electrode independent of said firsttransparent electrode and said second electrode.
 32. A method forproducing an electrochemical display apparatus, characterized bycomprising the steps of: forming a first transparent electrode on atransparent support; forming an electrolyte layer containing a coloringmaterial which colors by a coloring means and electrochemical reductionor oxidation, accompanied by deposition or dissolution; forming a secondelectrode having said electrolyte layer disposed between said firsttransparent electrode and said second electrode; and forming a thirdelectrode independent of said first transparent electrode and saidsecond electrode.